librarian2003 (librarian2003) wrote in weagardening, @ 2008-06-13 23:50:00 |
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Week 8 - Garden Wildlife Part Two
And here's the rest of it:
Some Bad Habits
Blackbird: Turdus merula
Blackbirds are most often seen in the morning or near dusk, as they pick around in the undergrowth for grubs and snails - though this forms only a small part of their diet, the main one being various fruits. Their foraging can be very messy as dead leaves and mulches are scattered around. They sweep their head from side to side using their bill like a plough to expose grubs and slugs. In newly planted flowerbeds where the mulch is preventing weed seeds from germinating, the effect is lost when soil is brought to the surface. Newly planted young specimens can be dislodged, and they pull up plant labels and discard them, though some disappear - probably to help in nest building. On the lawn the grass, moss and thatch they pull up is untidy as well. In the spring the males are very territorial and can be seen in chase flights with other birds. At this time decorative mirrors can cause casualties or even fatalities as they crash into them, so they should be covered at this time. To prevent the bark mulch from being scattered, try placing some twigs over it; they do not find it easy to work among them so go elsewhere; or pin strips of pond netting on the surface of the mulch along the edges where it will be tossed onto paths or the lawn. Keep the base of hedges cleared of leaf debris, this also reduces hiding places for slugs.
Elephant Hawk-moth: Deilephila elpenor
The Elephant Hawk-moth caterpillar is very large by usual standards here. As with nearly all Hawk-moth caterpillars there is a curved 'horn' or spine on the last segment. When alarmed it retracts its head to form a bulge and display the two spots which resemble eyes. This is the 'Elephant' look which gives it its name. The adult moth is marked in shades of pink and light brown. It feeds in the evening on nectar from honeysuckles and petunias. The main food plants of the caterpillar are Willowherbs. So perhaps it should be with the friends of the garden...
Froghopper: Philaenus spumarius
Froghoppers are small sap-sucking insects which are able to jump great distances if they feel threatened. The most common sighting is during early summer as cuckoo spit on stems and leaves when the nymphs secrete the protective froth over themselves as they feed on leaves and young shoots. This sometimes causes distorted growth. The adults are darker in colour and live openly on the plants, jumping away if approached. The damage is not usually severe and they do not need treatment. There is a risk of disease transmission if they move from plant to plant. If they are to be removed a squirt of water usually dislodges the cuckoo spit and the nymph. Permethrin can be used as a spray.
Hawthorn Shieldbug: Acanthosoma haemorrhoidale
A rather attractive bug which feeds mainly on haws, the fruit of the hawthorn bush, and its leaves in the springtime, it will also feed on White Beam and Oak. Relatively harmless and should be enjoyed rather than destroyed. The adults over-winter in crevices in trees, under pieces of bark or in grass tussocks. They emerge in April and the eggs are laid on leaves in batches of up to 24, the nymphs hatch shortly afterwards and look like miniature adults.
Pill Millipede: Glomeris marginata
The Pill Millipede is often mistaken for the Common Pill Bug (Armadillidium vulgare ). Both of them can roll up into a spherical shape in times of danger, but the way to distinguish them is the shiny, black appearance of the Pill Millipede's body and its many legs; the Pill Bug is a dull blue-grey and has seven pairs of legs. They have a similar diet and behaviour to their cousins the Millipede. Removing plant debris to discourage them is all that is required in most gardens. But the valuable contribution they make to the decomposition process in vegetable matter means that unless they are a direct threat to seedlings or crops, they should be left well alone.
Moth Pupae
There are hundreds of moths in the British Isles, most nocturnal, only coming into view at lighted windows and around outside lamps. Some of the prettiest are mistaken for butterflies. One of the most spectacular is the Hummingbird Hawk-moth or Clearwing, which is quite large and resembles a humming bird as it hovers while inserting its long proboscis into flowers to reach the nectar. But, it is the earlier forms in their life cycle which do not endear them to gardeners since they feed on plant material. Most of the caterpillars which attack garden plants belong to moths, either eating leaves, fruit or roots; eg. Codling Moths, lay their eggs in apples. They start as eggs laid on the underside of leaves, inserted into plant tissue or on the ground. These hatch into larvae (caterpillars) which go through several instars before pupating then finally emerging as adult moths. The pupae of some moths are found while digging as the larvae were previously feeding on roots.
Large Yellow Underwing Moth Caterpillar: Noctua pronuba
The larval stage of the Large Yellow Underwing Moth is one of the pests known as a cutworm. They develop between September and April above ground feeding on the stems and leaves of grasses and other plants, sometimes grazing them off at ground level. When disturbed it adopts a 'c'-shape. The adult moths appear between May and September. The underwings are more striking orange-yellow with a black band. They rest during the day in vegetation, and if disturbed will flash their bright underwings. They feed on the nectar of Ragwort, Red Valerian and Buddleja. While the damage caused by the caterpillars is not usually of great note, they should be moved to rougher ground if found among ornamental plants.
Knot Grass Moth Caterpillar: Acronicta rumicis
These fly between July and August, but in southern regions they can have a second brood which emerge in August and September. The caterpillars are covered in bristly hairs and feed on herbaceous plants such as Docks, Plantain and Bramble. They remain as a pupa over the winter.
Red Velvet Mite: Trombidium sp.
This Red Velvet Mite is of the genera Trombidium one of the many species in the Trombidiidae or Velvet Mite family. The body is covered in fine hairs giving it its 'velvety' appearance. It is usually found in the soil or mulch and feeds on vegetable matter. The larval stage which has six legs, is about one tenth of the size of the adult and lives on blood from animals and sometimes humans. As it feeds it releases an anticoagulant which can cause an allergic reaction resulting in a rash.
The adult mites have eight legs.
Song Thrush: Turdus philomelos
The Song Thrush is found throughout the British Isles and mainland Europe. Numbers have declined over the last century and it is now in the red category of conservation importance which means that there has been a rapid change in the past 25 years. The garden birds tend to be resident, but there is a migration in the winter from colder regions depending on the severity of the weather. They travel at night. Scandinavian birds come to Britain and some British thrushes move to Northern France, Iberia or even North Africa. They are omnivorous, feeding on earthworms, slugs, snails and other invertebrates along with fruits and berries. They use an 'anvil stone' to smash open snail shells and the "tap-tap" sound can often be heard in the garden. As with their close relative, the Blackbird, they can be a nuisance in the garden as they scatter mulches and leaf-litter in their pursuit of invertebrates. They are more shy though, keeping close to cover from shrubs and trees.
Wasp: Paravespula vulgaris
There are over 30,000 different species of wasps, some are used in horticulture as biological controls. The best known is the Yellow and Black Wasp, Paravespula vulgaris which although feared by many, is also useful to the gardener, eating harmful flies and aphids as well as caterpillars. They have a 'sweet tooth', also eating nectar, refuse and fruit. At the end of autumn, all of the wasps die except mated queens, which burrow into leaves or soil to spend the winter. In the spring the queens emerge and start the nest building process. By the end of the summer the nest may contain 20,000 or more wasps. The final generation of the season has drones and queens which mate for the next year's population.
Treatment
The wasps are more likely to be a nuisance in the autumn when they no longer have larvae to feed and go in search of ripe fruit and other sweet things. However they usually sting in response to a perceived attack which can be accidental if they become trapped in clothing or a nest is approached - button up clothing while picking fruit in the late summer to prevent a curious wasp crawling in while drowsy from eating a sugary meal. Also flapping wildly at their presence is likely to provoke a response so it is best to stay calm and move away slowly or wait until they fly away. However if you are close to a nest they will come straight for an attack and the first you may know about it is the strike. If uncertain how to deal with a nest, leave it to a professional. Do not flood or damage it without first killing the occupants, this is best done in the evening when the wasps have settled for the night, using a powerful knock-down insecticide recommended for the purpose. They are attracted to food and refuse so if eating outdoors keep food covered until ready to eat; remove over-ripe fruit from trees and pick up windfalls; keep rubbish bins covered. Jars of sweetened water can be placed around as traps to attract and drown them. Insecticides are usually supplied as a powder which is puffed into the entrance of the nest. There is also a foam spray available that can be aimed from about 2 metres away, which is safer to use. Both types can be purchased at hardware shops or a garden supplies stockist and should be used late in the evening or the early morning when the wasps are relatively inactive. Nests inside buildings such as in a garage roof, can be dealt with using a fume insecticide containing permethrin. It is supplied in a can and is lit to release the fumes while the area is left for a few hours. It will kill most other creatures in the enclosed area as well, such as spiders and flies.
Common Rough Woodlouse: Porcellio scaber
Like millipedes, they are detritovores feeding mainly on plant debris, although seedlings are sometimes attacked. Their ability to break down larger particles of organic material makes them an important part of the rotting process. In the commercial glasshouse they will damage the stems and lower leaves of cucumbers, but are only a problem in the domestic setting around young seedlings. Rotting timber and brickwork provide a suitable hiding place, so removing these from near vulnerable plants is helpful. Removing plant debris to discourage them is all that is required in most gardens. Diatomaceous Earth is a mined product and consists of tiny fossilized diatom remains. It works by sticking to the exoskeleton of the woodlouse by static attraction and abrades it as it moves around resulting in holes which lead to dehydration and death. It is applied as a fine powder to paths and areas where crawling invertebrates are present.
Enemies
Aphids
There are over 500 species in Britain, fortunately only a few are garden pests; most are specific to one or two plant species. The Peach - potato aphid (Myzus persicae) is the green one which is most often seen on a wide range of plants, but can range in colour from yellow, all shades of green, to pink, red and almost black. There are root aphids which attack below ground and with a severe infestation will kill the plant by removing the sap before it can rise up the stem. They are white and waxy, giving them the appearance of a fungus. The usual symptom of their presence is distorted, weak growth of leaves and shoots. A large infestation can cause roots to reduce in size due to the sucking activity of the aphids increasing the transpiration stream, so the plant requires fewer roots to supply the volume of water by normal means.
Treatments
Where only a few are present they can be rubbed off affected shoots, after a while natural predators will arrive and remove them. A hose with good force can be used to dislodge them from tough-leaved vegetables. Placing aluminium foil or a mirror below plants, fools them into flying upward.
A spray prepared from a couple drops of washing-up liquid to a gallon of water as an acceptable organic method of control; so are insecticidal soaps made from plant fatty acids. Avoid spraying in sunshine to prevent scorching the plant.
Biological controls need a constant supply to survive, so there will always be a low-level presence, hopefully these will be on nearby wild plants. Ladybirds are nocturnal so if they are feeding during the day the number of aphids may be low.
For chemical control use pyrethroids or bifenthrin - spray as late in the day as possible to avoid Ladybirds and other friendly creatures. There is evidence that Myzus persicae are developing resistance to the pyrethroids and Primocarb so it is best to vary the chemicals used to reduce the chances of this happening.
Companion planting using partner plants which deter the aphids, eg. Borage to deter Black Bean Aphids.
Big Bud Mite: Cecidophyopsis ribis
As the mites feed the buds become enlarged and more rounded than pointed, fail to develop properly and eventually wither. As well as damaging the buds the mites can carry the currant reversion virus which alters the size and shape of the leaves, further reducing the vigour of the plant and fruit production suffers. Gooseberry and Red Currant bushes should also be checked for their presence. The mites breed in the buds during summer and autumn, overwintering there then increasing their numbers from January onwards ready to disperse as the buds open. They are only capable of crawling short distances so are carried to young healthy dormant buds by other insects, washed downwards the rain and on the wind. These dormant buds develop the following season. Infestation usually occurs in the late spring or early summer so the bushes should be checked carefully and affected buds removed. If most of the branches are infected the entire bush should be destroyed. Growing nettles nearby is said to provide shelter for predatory insects and improve fruit yields.
Derris or pyrethrum can be used when the leaves are just emerging, after any enlarged buds are removed and burnt, but chemical control is not usually successful. If reversion disease has occurred there is no remedy so the bushes should be burnt. Use only healthy plants from a certified source and plant in a new site if possible following an infestation.
Large Cabbage White Butterfly: Pieris brassicae
The caterpillars will be found on cruciferous crops, eg. cabbage, swede, kale, throughout the summer. The adult, nearly all-white butterfly emerges from the pupa in April and May. The adult male has black markings on the tips of its wings; the female has the same marks with the addition of two black spots in the middle of each wing. After mating the female lays 20 to 100 yellow eggs on the underside of cruciferous plant leaves. This first generation pupates in June in a crevice or woody stem, emerging in July as the second generation which usually causes greater damage to crops in the garden, repeats the cycle and pupates to overwinter for the next year. They will use wallflowers and other cruciferous plants (four-petalled flowers), as alternate hosts. If the damage is extensive and the leaves look torn, the culprits may be pigeons. Slugs will also strip the leaves, but there will be a slime trail.
Treatments
Inspect the leaves of cabbage and turnips in July when adults are seen, for eggs and small caterpillars - crush by rubbing with a finger. They are usually around the outer edges where the female probably has a better grip while she places them in clumps.
Covering the target plants with horticultural fleece or fine netting should prevent the butterflies laying their eggs in the first place. Netting should be held away from the leaves and not draped over them otherwise the butterfly may reach them.
Starlings are another predator.
The caterpillars can be sprayed with Azinphos-methyl or derris with a wetting agent to keep the droplets on the waxy brassica leaves.
Small Cabbage White Butterfly: Pieris rapae
The Small Cabbage White Butterfly larva is probably the most destructive of all of the caterpillars, devouring cabbages and other cruciferous crops all over the world. It is distinguished from the Large White by its smaller and less pronounced black markings. The adult male has one spot on the wing and the female has two - both have a pale yellow underside to the wings. After mating the female lays eggs, usually singly and close to the edges, on the leaves of cruciferous plants. They can be on the lower and upper surfaces on the leaves. The light green larva which hatches out usually occurs on its own, whereas the mottled larvae of the Large White are found in clusters initially. The Brimstone Butterfly (Gonepteryx rhamni) with bright yellow wings, has a similar coloured larval stage. As with any destructive caterpillar, crush them or spray with insecticide if the infestation is widespread.
Gooseberry Sawfly Larva: Nematus ribesii
These attack the leaves of gooseberry bushes; also red and white currants, but not black currants. The adult female lays its eggs on the underside of the leaves at the centre of the bush close to the ground. When they hatch the first instar of the larval stage is very small and makes tiny holes in the leaf. The next stages are much bigger, and they cause the most damage, stripping the bush bare as they move outwards along the branches. The caterpillar-like larva is light green with black dots and a shiny, black head. If disturbed it clings to the edge of the leaf while bending into an S-shape. All of the leaves can disappear with only the stalks and a few veins remaining. Check any leaves beyond them and the larvae will be there, so they can be rubbed off. The lack of foliage weakens the bush and it produces a very poor crop the following year.
Aquilegia Sawfly Larva: Pristophora aquilegiae
The larval stages of the sawfly are the pest with this insect. They can defoliate Aquilegia or Columbine plants, leaving only the leaf veins and stalks. Although they look like small caterpillars, they develop into a non-stinging wasp-like fly. The eggs are laid on the undersides of the leaves and when they hatch in April, the larvae eat from the edges towards the midveins. Check the leaves during April and May for signs of damage or even the eggs. If caught early the larvae can be picked off by hand or sprayed with insecticidal soap. Imidacloprid can be applied as a drench to the soil early in the season to catch the overwintering cocoons and it will be taken into the plant to work systemically as well, killing the larvae as they feed. A general contact insecticide can be used, particularly to the undersides of the leaves when the small larvae have not done much damage - do not use during flowering to avoid killing bees and other pollinating insects. There is thought to be only one generation in a season so once an attack has been cleared the plants should be free of them. If the attack is severe, cutting the foliage to the ground tidies up the plant and allows a new flush of growth.
Cockchafer: Melolontha melolontha
The fat white larval stage of the Cockchafer Beetle is quite destructive to cereal and other grass plant roots. They live in the soil for three or four years and are sometimes called Rookworms as Rooks are said to be particularly fond of adults and larvae. The adult beetles are also destructive, feeding on flowers and foliage. They are usually found in rough grazing or cereal crops and in new gardens. Turning over the soil exposes them to the birds. There is now a biological control which uses a parasitic nematode called Heterorhabditis megidis. It is applied to moist soil from late July to September when the grubs are most active close to the surface and the soil temperature is above 12C / 50°F. For chemical control Provado Lawn Grub Killer which contains Imidacloprid is a recent introduction for the treatment of Leatherjackets and Chafer Grubs.
Carrot Root Fly: Psila rosae
The creamy-yellow larval stage of the Carrot Fly is very destructive to carrots, first burrowing around the outside, eventually tunnelling throughout the root. They are slender, without legs, and up to 1cm long. Parsnips, celery, dill, angelica and fennel can also be attacked. Ground-elder, hemlock and other umbelliferous plants such as Cow Parsley can act as alternative hosts. Affected plants show yellowing of the leaves, young plants can wilt and die, but usually recover and become stunted. It is frequently the cause of parsley failing to thrive, the seeds germinate, grow for a while then become yellow and spindly. The carrot root shows rust coloured tunnels around its circumference, not to be mistaken for cavity spot, a fungal disease causing elongated sunken spots on the surface. In parsnips the damage is usually near the crown and bases of the leaf stalks. The adult fly is about 8mm long with a shiny, blackish body similar to an ant with wings, the head is reddish-brown and the legs yellowish. They tend to appear periodically and are most prevalent when native umbellifers are in bloom, eg. Cow Parsley - there is an old practice of sowing carrots either before or after blooming occurs. The female flies lay their eggs in the soil beside the host plants. Usually there are two generations per year, the first emerging in late April to early May and a second in late July. They overwinter as larvae in roots or as pupae in the soil, though a few adults may survive the winter.
They are low fliers rarely going above 50cm so one control is to surround vulnerable plants with a polythene barrier about 60cm high or to cover completely with garden fleece. Lifting the crop in autumn limits the damage. Sowing the seed very thinly to reduce thinning and removing any thinnings, limits the attack as they are attracted by the smell of the crushed plant. Delay sowing until May to avoid the emergence of the first generation. Avoid growing early and late crops together and if infestation occurs do not leave any roots in the ground to carry over to the next season. Sowing at the correct time will avoid the flying insects. If sown in early June, the first generation females will have nowhere to lay their eggs so there should be fewer second generation flies to emerge. Other sowings in late autumn or early spring for harvesting in the summer should be at lower risk. Harvesting before the second generation can do too much damage is important so lifting the June sown carrots by November should reduce their exposure to damage. Any left after this will be vulnerable and can provide overwintering quarters for the grubs. Companion planting or interplanting has also been tried, to put the females off the scent using onions or garlic. This is not totally effective as the flies use other methods to locate, although spraying the crop with a concentrated garlic extract has been tried. Commercially a plant called medic (Medicago litoralis) a type of clover, has been tried. There are also resistant cultivars of carrot, eg 'Fly-away'. The genetic modifiers are developing chocolate flavoured carrots to entice children - maybe the carrot flies won't like chocolate.
Leatherjacket: Tipula paludosa
The larval stage of the Crane Fly feeds on the roots of grass causing yellow patches; they will also attack potatoes, strawberries, cabbages and lettuce if they are planted in newly cultivated grassland. Pot plants can also be attacked and can be greatly reduced in vigour or even killed - bulbs may never emerge if the young shoots are eaten away. Birds and Badgers find them a good source of food and cause unsightly marks on the lawn as they forage for the grubs. The female lays about 300 eggs on the soil surface after mating. They hatch in autumn developing until late spring. Pupating in the summer, the adults emerge in autumn to begin the cycle again. A cultural control to use is covering a well-watered patch of grass overnight with a sheet of black plastic or a tarpaulin, the leatherjackets rise to the surface into the moist space. At dawn they can be swept up or left for the birds. Starlings love them and can be seen in flocks feeding on infested areas. Digging over affected areas and a summer fallow, will allow the birds better access. This is not an option when they are causing dead patches in the lawn and there is now a biological control which uses a parasitic nematode called Steinernema feltiae. It is applied to moist soil from late August to October when the soil temperature is above 10C / 50°F and the young leatherjackets are active. They are also effective against Cockchafer Grubs. Turn out potted plants to see it leather jackets are present, there will probably be tunnels around the edges. Provado Lawn Grub Killer which contains Imidacloprid is a recent introduction for the treatment of Leatherjackets and Chafer Grubs.
Leaf Beetle
Leaf beetles come in many colours and sizes, and are usually specific to a few related plants. They usually appear in late April and the females develop enlarged abdomens so the elytra (hard wing case) cannot close properly. This is due to the eggs which they lay in clumps on the underside of leaves. The small black first instar larvae, about 2mm long, graze on the lower side of leaves; the later, larger black instars perforate the leaves like the adults. The most immediate and effective option is to pick off the larvae and adults, and crush the groups of orange-coloured eggs to try and reduce the damage. A fatty-acid based spray forms a scum on the body of the adults and larvae causing them to expire. Other damaging Leaf Beetles include the Red Lily Beetle Lilioceris lilii, which attacks bulbous plants, especially lilies and fritillaries.
Soft Brown Scale Insect: Coccus hesperidum
Soft Brown Scale Insects are a bit like minature turtles in shape and are about 2 to 4mm long. The older females are dark brown and are usually found along the centre vein on the underside of a leaf where they suck the sap. They excrete 'honeydew' which is full of sugars and drops onto the lower leaves or anything below - it attracts other insects such as ants and wasps to feed on it. Also you may find nymphs, known as crawlers as they are able to move around. The older females lose their mobility and eventually die, but their shell remains to protect the eggs. Reproduction can be sexual or asexual (parthenogenesis) - every female may be capable of producing progeny without fertilization. The eggs hatch into first stage nymphs, or crawlers, when they are laid. These move out to find feeding sites within a few days. After about a week, they moult into the second stage, a passive nymph. Adult males and females emerge in about a month. The males have wings and are rarely seen. There can be up to six or seven generations a year indoors, so a colony can rapidly grow. They attack vines, currants, cotoneasters and seem to prefer citrus and bay trees. The leaves become yellow and the shrub fails to thrive. A secondary infestation of Sooty Mould is usually the indication that the little beasts are present. The upper surface of the leaves become blackened by the mould which is living on the honeydew that the scale insects have excreted. Remove the scales if the plant is not too big, using your fingernail or a toothbrush to scrape them off on tough leaves like bay. This will probably have to be repeated a few times, but you should win in the end if you persist. They have a waxy cuticle so contact insecticides have little effect, the best type to use is a systemic insecticide like Provado. The best time to attack them is at the pale brown juvenile stage when they have not yet developed their waxy coat fully.
Midge
Midges are attracted by the carbon dioxide (CO2) exhaled by all animals and are thought to be able to detect it from 200 metres away. Activity is mainly at dusk or dawn, but they can also be present during daylight hours in the shade among trees and in dull weather. They are found in damp places where there are suitable sites for breeding. The larvae are detritovores, feeding on dead plant material in wet peat or in the silt in lakes and ponds, so they are an important part of the cycle which breaks down this debris. The adults are also an important food source for birds and bats. The females must feed on blood to ensure that the eggs they lay will survive.
There are two batches of eggs laid in a season. The first is larger in number, but does not require the blood meal, so it is the second batch produced in late summer and autumn which leads to the biting frenzy. The first instar larvae which hatch, burrow into the moist ground and after three more instars emerge to increase the population greatly. The adult females from this generation do all the biting and the larvae they give rise to spend the winter underground to emerge as the adults of the following spring.
Treatments
Over the years there have been many potions devised to repel the onslaught of the midges.
Farmers have used walnut leaves which are rubbed along the backs of cattle to act as a repellant.
Other aromatic foliage such as Artemisia 'Powis Castle' or Cotton Lavender (Santolina) may work as well.
There are many liquids and gels which can be applied, they are mostly based on Citronella oil or synthetic chemicals such as di-methyl phthalate and di-ethyl toluamide.
It has been shown that dark colours attract the midges so it is best to avoid dark clothing when they are known to be about.
Taking two dessertspoonfuls of distilled vinegar a day is said to ward off biting insects as it taints the perspiration so it will have an unpleasant smell for a while.
Try to avoid their habitats at dawn or dusk and during dull weather.
New Zealand Flatworm: Arthurdendyus triangulatus
The New Zealand Flatworm lives on earthworms and will greatly reduce their population, sometimes to below detectable levels. They have flat, purple-brown bodies with buff-coloured undersides and edges, pointed at both ends and covered with a sticky slime. At rest they are about 1cm wide by 6cm long, extending to about 12cm when they move, but narrower. They are usually found coiled up with a 'halo' of slime under pots, stones, wood or pieces of polythene, where the surface is damp.
Reproduction is asexual by parthogenesis, ie. no mate required. A soft white sack swells from a temporary opening in the back of the worm near to the rear end. The white liquid content does not have any wormlike structures at first. The opening in the worm heals leaving a whitish scar for a short time. The hard, shiny black outer coating forms over the surface to give it physical protection and to prevent it from drying out. Two to eleven small flatworms develop inside the oval shell which is about 7-8 mm by 5mm across. New Zealand Flatworms are a great threat to soil condition and the wildlife which feed on earthworms, and every means should be employed to prevent their spread and eradicate them if possible. There are no approved chemical controls, but Ground and Rove beetle adults and larvae are known to prey on the adults. Birds have taken them as well, but because of their habitat they are rarely exposed to them. By adding lots of organic matter the population of earthworms can be improved. It is possible to trap the flatworms by laying sheets of black polythene, or placing bin-bags of compost around and collecting any which congregate underneath. They can be moved to another site accidently if they cling to a bag or plant pot. Chopping them up may not be enough to kill them. So grind them up between two stones, add to very salty or boiling water, or burn them.
Red Lily Beetle: Lilioceris lilii
The bright red body, black legs and head make Lily Beetles very striking in appearance, but they are very destructive to bulbous plants and in particular Liliums such as Turk's cap lilies, Asiatic lilies, Oriental lilies, Tiger lilies and some Fritillaria species. From spring to autumn the adults and larvae feed on the foliage, flowers and stems. The removal of the leaves deprives the plant of food production which severely weakens it and may prevent flowering the following year, or in severe cases kill the plant. The Lily Beetle is native to mainland Europe and Asia, but not the British Isles. In the spring the adults climb out of the soil and after mating the female lays her bright orange eggs in lines under the leaves of Lily plants or Fritillaries. The orange larvae eat through the foliage, working from the tip to the stem. They cover themselves with their sticky black excrement to act as a deterrent to predators, so the orange colour disappears and they are more difficult to spot. The larvae cause most of the damage and spend two to three weeks stripping the foliage, then the flower buds before dropping to the ground to pupate. After two to three weeks the bright orange pupae have metamorphosed into new adults which climb into the plants to continue the cycle. Mating can occur from spring until autumn and surviving adults move to the ground to spend the winter. The adults have been found on other plants including Lily of the Valley, Solomon's seal and Day Lilies. The larvae have only been found on bulbous Lilies and Fritillaries.
Treatments
The recommended method of removal is to check affected plants regularly picking off and crushing any adults, eggs or larvae. The adults tend to drop to the ground with their black undersides showing when the plant is disturbed so they are easier to find if a light-coloured material is placed there first.
Due to the difficulty in spotting the larvae a follow-up treatment with an insecticide is advisable - one containing Imidacloprid such as Bio Provado Ultimate Bug Killer (Imidacloprid and Sunflower Oil).
As a preventative the insecticide can be applied to the soil in the spring to eliminate the overwintering adults before the lilies start into growth.
A more "friendly" insecticide made from extracts of the Neem tree is also effective when applied to the early stages of larvae. It kills them and deters the adults. There are no biological controls, but they are attacked by parasites in their native areas.
There are a few preventative measures which can be taken, such as checking new bulbs for larvae before planting. Probably the most likely method of spread is the recent trend of buying established lilies in pots.
Woolly Aphids: Erisoma lanigerum
Woolly Aphids get their name from the waxy excretion they carry as a form of protection from predators. At first inspection this may make them appear to be a fungus. They usually appear in the spring on some fruit trees and shrubs such as apple, pear, prunus, pyracantha, cotoneaster, elm, hawthorn and mountain ash. As with all aphids they are sucking the sugary sap, but their action causes a callous-like lump or gall to grow, which provides better access to their reward. These remain after an infestation has gone and affected branches do not usually regain their vigour so if possible they should be pruned out. If a plant is badly infested it may never recover properly and it may be best to replace it. The galls cause cracking of the bark and can allow diseases such as Canker to infect the tree. The adults are about 2mm long and a pinkish-brown colour, although they appear to be white with their waxy protection. They overwinter as young in crevices and cracks in the bark, emerging in the spring forming rapidly growing colonies on new shoots and at pruning cuts where the sap is more readily available. This causes weak growth of the plant and the leaves may fall due to the lack of sap to keep them functioning. They also excrete honeydew which coats the leaves and Sooty Mould may start to grow. Each adult can produce up to five live young per day and after a few generations winged adults develop to spread to new branches and nearby trees. There are other Woolly Aphids such as the Beech Woolly Aphid which is specific to Beech trees and infest the leaves.
Treatments
Check susceptible plants regularly for infestations and treat pruning cuts with a wound sealant to remove this source of sap.
The colonies can be rubbed away with a brush and soapy water.
A forceful jet of water will remove the bulk of a colony.
Use a cloth soaked in methylated spirit to 'brush' them off.
A spray prepared from a couple drops of washing-up liquid to a gallon of water as an acceptable organic method of control; so are insecticidal soaps made from plant fatty acids. Avoid spraying in sunshine to prevent scorching the plant.
Encourage birds such as Blue Tits to the area by supplying feeders and nest boxes.
Place Ladybird and Lacewing shelters nearby to provide winter quarters for them. These can be specially made structures or bunches of dried, hollow stems tied together and placed horizontally in a sheltered spot.
Daisy-like yellow flowers attract insects such as Hoverflies and Lacewings and their larvae feed on aphids.
Biological controls need a constant supply to survive, so there will always be a low-level presence, hopefully these will be on nearby wild plants. Ladybirds are nocturnal so if they are feeding during the day the number of aphids may be low.
For chemical control use imidacloprid, pyrethroids or bifenthrin - spray as late in the day as possible to avoid Ladybirds and other friendly creatures. Follow directions and precautions given on packs, especially if treating fruit trees.
Vine Weevil: Otiorhynchus sulcatus
Their presence is shown by semi-circular notches eaten into the edges of leaves, most notably on evergreen shrubs like Rhododendron, Euonymus, Azalea and Camellia. This damage by the adults is not fatal, just unsightly (although is a good indicator that there will be eggs, and larvae hatching in the autumn). The real damage is done by the larvae which feed on the roots, often killing the plant, especially potted and young plants. The first sign of the presence of the larvae is usually yellowing leaves, poor growth and a wilting plant which does not respond to watering. Unfortunately it is often too late to save the plant. Rescue is possible if the damage is not too extensive; wash off all the compost to remove the grubs and remaining eggs, then replant in fresh growing medium. Some plants are more at risk from attack than others, eg. Sedums, Primulas, Fuchsias and Impatiens, but most plants in pots are at risk. They emerge from the pupa stage in late spring and after feeding on plant material for 21 to 45 days they are ready to lay eggs; between 500 to 1600 eggs over a one to two month period. They hatch 10 to 12 days later and the larvae burrow down to the fine roots. A prepupal stage develops in December and remains like this until late spring when it pupates fully for a few weeks before the adult emerges. Conditions for eggs and larvae are optimal when soil moisture is moderate to high in July and August. Heavy mulches help to maintain moisture levels, so removal of excessive mulch layers and minimal watering of plants during this period is detrimental to their survival. (Unfortunately surface rooted shrubs such as Camellias need to be well watered at this time to set the flower buds, so this must not be missed.) Excessively damp soils in the autumn also force larvae to move up the base of the plant where girdling can occur, so good drainage around the plants will ease the problem. Indoors, the warmer conditions mean that they can reproduce all year round so all stages of the life cycle can be present at all times. If the plants are in pots and on a stand place the legs in water as the adults do not swim so cannot climb up - only useful for rust resistant legs and not wood either. A natural predator is the Centipede which eats both eggs and larvae.
Treatments
Provado - the systemic insecticide, Imidacloprid applied to the growing medium as a drench, lasts for a few months and kills the larvae which do the damage. It cannot be used on edible or cropping plants such as strawberries.
Levington Plant Protection Compost - contains Imidacloprid a systemic insecticide, and used as the growing medium gives protection for about six months. Follow the instructions carefully and buy only what is needed as it loses its potency if stored.
Nematode - Steinernema kraussei - a microscopic eel worm which kills the larvae, is a recently discovered species that works down to 5°C so it can be applied over a longer period outdoors. It is best used between August and November when the weevil eggs are hatching and again from March to May when the soil is warm enough and the larvae are active. The protection lasts for about four weeks - trade name Nemasys Vine Weevil Killer or Grubsure.
Nematode - Heterorhabditis megidis another species of eel worm which enters the grub and carries bacteria that kill it. The nematode reproduces using the dead grub as food. It is also temperature sensitive and works best at around 12°C. They die out if no grubs are present.
Traps - corrigated cardboard has been used, made into a roll and left for the adults to hide in during the day. Moist sacking laid on a path provides a dark daytime hiding place for the adults, which can be collected during the day when they are relatively inactive. Night-time sorties with a torch might show results, but the adults are quite active and difficult to catch.
Foliar insecticide - plants which are attacked by adults can be sprayed with insecticide starting in the late spring and repeated during the summer to kill them before the egg-laying period in late summer
Sacrificial plants - primulas, polyanthus and cyclamen are some of the favoured plants for adult weevils to lay their eggs beside. Some of these potted in Levington Plant Protection Compost and left beside your treasured plants will attract the adults, which will lay their eggs in the compost and the larvae will be killed when they hatch and begin feeding. You could use Provado to treat the sacrificial plants instead.
Rabbits: Oryctolagus cuniculus
Descended from ancestors in Eastern Asia, rabbits were introduced to the British Isles in the 11th century by the Normans who used them for food and fur. In those days they were a valuable commodity and Warreners, employed to look after them on large estates, lived in fortified houses so that they could fend off poachers. In later centuries they were taken around the world for similar reasons, much to the regret of most of the new host nations. When they attack an established plant it usually survives, but is weakened and unsightly - young plants and seedlings do not. The foliage is grazed off and the roots are excavated - often they do not even eat the young branches and foliage, leaving the evidence to annoy the gardener. In the winter when food is more scarce they will eat tree bark, usually the smooth bark on young trees, often killing it. Plant roots are also vulnerable and sometimes the edges of perennial plants are excavated for a meal. In the vegetable plot, carrots are favourite, just as the storybooks tell us, and they will burrow down into a drill of potatoes to reach the tubers. The damage they cause is not always detrimental as their grazing keeps areas in rough scrubland clear of bushes allowing some other plants to thrive. This was seen during their decline in the 50s and 60s when the scrub regenerated and some other wildlife lost their habitat - eg. the Large Blue Butterfly (Maculinea arion). became extinct in Britain; it lays its eggs on wild thyme flowers and this died out when the rabbits were not keeping more dominant plants grazed down. They are social animals, usually living in groups with 2 or 3 males (bucks) and 3 or 4 females (does), raising their young in the main warren or in a blind tunnel among weedy undergrowth, tall grass or brush, known as a "dig" or "breeding stop". If a rabbit decides to make a breeding stop in the garden it is very persistent, re-digging if it is filled in - even a year later in the exact spot and at the same angle of dig. Each group has a territory and they rarely go more than 500 metres from home. When conditions are favourable they can establish large underground warrens going down about 3 metres in sandy soil, and supporting about 100 rabbits. As nocturnal animals they are most active from dusk until mid-morning, spending the warmest and brightest part of the day in a shaded area or in their burrows. Their natural predators are foxes, stoats and cats; young rabbits are taken by buzzards, badgers, and weasels.
Rabbit Deterrents
The most effective way to deter them is to erect a netting fence around the garden at least 60cm high and buried slightly at the base.
Trees should be planted with a suitable protector around the base.
A guard for small, vulnerable plants can be made from a plastic drinks bottle with the top and bottom removed and held in place with a short cane.
For larger plants a loop of netting wire can be erected around each one or surrounding a whole bed. A more aesthetic barrier of small branches can be pushed into the ground around the plant.
An upturned hanging basket makes a protective dome for low plants.
These all take away from the full appreciation of the plants, but usually the rabbits only seem to concentrate their attacks on newer planted beds, so the protection may be removed the following year, when they are established. In winter if the snow is deep the fence or planting guard can be breached so the snow should be cleared away.
A fence is not always practical or aesthetic in the ornamental garden so various concoctions have been devised over the years to deter the rabbits - with doubtful success in some cases. They usually require constant application, especially after rain.
A spray of equal parts of water and ammonia with a few drops of washing-up liquid to improve dispersal, sprayed around the plants (not on them).
The fungicide thiram is obnoxious to rabbits and is formulated as a repellent as well: there are also pepper derivatives.
A solution of colophene in alcohol can be soaked into rags and placed around the area on poles.
Planting foxgloves around a vegetable plot is supposed to guarantee a rabbit-free area (probably the foxes that come around to try on the gloves scare them away).
Others include mothballs, cat fur clippings or fox urine, but how many cats would you need to shear, how do you find a fox urinal and the aroma in the garden would put most people off as well!?
Tiger manure can be purchased from some zoos, and is said to be very effective.
A device with a detector linked to a hose pipe which delivers a squirt of water can work for a while, but should be moved around to confuse, and remember to turn it off when you go into the garden.
One of the most effective deterrents is the pet cat or dog which leave their scent around. Feral cats are helpful as well.
There are published lists of plants which are 'rabbit resistant', but young rabbits tend to nibble at any plant to see if it is tasty and excavate the roots, sometimes dislodging the whole lot. Plants with caustic sap, spines, tough leathery leaves or very aromatic foliage are not usually on the menu.
Slugs
Of the 29 species in Britain a few are carnivorous, but most live on living and decaying plant tissue. Instead of a shell like the snails, slugs have an internal horny plate covering their breathing cavity. There is a range of colours and sizes of slug depending on the species. Slugs begin to move, hatch, feed, and lay eggs when the temperature is above 5 °C. During dry and cold conditions they remain deep in the soil. They are usually nocturnal, but will venture out on dull, damp days. There are three stages in the life cycle: eggs, immature stage and adults - they can overwinter in any stage. They are hermaphrodite having both male and female organs, so every individual can lay eggs - up to 300 each in batches of 10 to 50 in moist, but not waterlogged, crevices; sometimes down the sides of pots. One individual has the potential to produce about 40,000 offspring. Eggs are gelatinous, watery, about 3 - 4mm across and usually spherical like tapioca. The period of development of the eggs varies depending on the temperature, during warmer weather they hatch after 10 days, but this can be up to 100 days in cooler conditions. After hatching the slug matures in less than a year and can live for two or more years.
Treatments
There are many suggestions to kill or deter this pest, but even the most diligent collection regime has been shown to have little effect on the damage caused. The best thing is to try and cope with them by following some general hygiene methods.
Remove their hiding places and spots where they lay eggs, eg. rotting boards, logs, stones dead leaves and other debris. Place compost heaps away from vulnerable plants. But don't be too tidy as Ground Beetles which feed on the eggs, like to hide during the day as well, large stones and pebbles will do for them. Another creature which appears to eat the eggs is the New Zealand Flatworm.
Some other means of control:- use traps, eg. stones, boards, upturned pots empty grapefruit skins or wet sacking, the slugs take cover underneath and can be collected. They will also lay their eggs here so they can be destroyed as well.
go slug hunting at dusk and chop them up or put them in hot water, this is the most effective method of reducing their numbers, but the most destructive species do not emerge often. The slimey bodies are not very pleasant to handle so use tweezers or chopsticks.
Ordinary table salt is lethal to slugs, but overuse is detrimental to plants and other creatures. It is probably best to drop them into a container of this, rather than sprinkling it about.
A tablespoonful of oats acts as an attractant when placed beside more favoured plants. The slugs can be collected and destroyed.
Attract hedgehogs into the garden with dog food (not bread - it clogs their digestive system and milk is bad for young hedgehogs). Keep them there with a concealed, dry home with straw bedding and don't light bonfires without checking for them.
Beer traps should have the entrance about 3cm above soil level to prevent Ground Beetles falling in - put a few twigs inside to help any which do fall in, to climb out. Beer cans can be quite effective. Slugs are also partial to cat and dog food, so this too makes a suitable bait. A home-made trap can be constructed from an empty margarine or ice-cream tub with a hole cut in the side near to the top - the lid makes escape more difficult and stops the trap filling up with rain water.
Frogs, toads, hedgehogs, some beetles and their larvae (ground & rove), centipedes, parasitic flies, birds, chickens, and ducks are natural enemies. Attract these creatures by providing shelter like a thick hedge
A dry mulch will reduce slug activity, this is achieved using a dutch hoe in dry weather. Alternatives are grit, sawdust, cocoa shells, weathered cinders, wood ash or crushed egg shells. However their protective slime can allow them to crawl over a razor blade or sharp glass, so these methods are of limited success at best and are usually wishful thinking!
Diatomaceous Earth is a dry granular substance made up of fossilised algae. It is applied as a barrier to exclude the slugs. It loses its effectiveness when wet, but regains it after drying out. Also can be used to eliminate other insects the dry powder sticks to their exoskeleton, abrading it and leading to dehydration.
A copper wire or strip placed in a circle around the area is said to deter by creating a micro-current as the slug touches it. Check for the presence of slugs or their eggs first and destroy - there is no point in trapping them inside! Strips around pots could also be decorative. A self-adhesive copper tape is available in some garden centres or online. There is also a woven mesh which can be erected as a small fence, but it must be in contact with the soil along its full length otherwise they will crawl underneath.
Cut the bottom off a plastic drinks bottle and remove the cap, to form a protective cylinder around vulnerable young plants.
A biological control is the nematode (eel worm) Phasmarhabditis hermaphrodita which occurs naturally. They invade the slug and bacteria which they carry cause the slug to stop feeding, go underground and die. As they decompose the eel worms reproduce. This natural control is less effective on surface dwelling species as the eel worms live in the moist conditions below ground, but they are the best treatment for the underground species which attack root vegetables. Nematodes are unaffected by wet weather. They remain active for about 6 weeks, and need a minimum temperarure of 5°C.
A slick of petroleum jelly around the top of containers prevents them crossing to the contents, but makes handling the pots difficult and it becomes covered with dust and leaves.
For use when on slug patrol, make a half-and-half mixture of vinegar and water in a handsprayer. One squirt should kill them. Also a 1 : 3 mixture of household ammonia in water should work.
Slug pellets
Another slug bait is one containing ferric phosphate which works best in moist conditions. It is considered to be organic and although it is less effective than metaldehyde, it can be used where crops are grown and is not hazardous to pets. It degrades over time in the soil to iron and phosphate.
Some species or varieties of vulnerable plants with thicker leaves are said to be resistant.
Sacrificial plants such as lettuce planted near to vulnerable ones, may draw the slugs away and keep them interested for long enough to be picked up and removed.
Keeping vulnerable plants such as hostas in drier conditions makes the leaves tougher and a bit less attractive to slugs.
Snails
Snails are similar in most ways to Slugs apart from their shell. They are usually found during the day behind stones and clinging to walls where they are sheltered by a climbing plant. They become active at night or occasionally during dull moist days, when they can avoid predators and drying sunshine. They can live for about three years. Major predators are the Song Thrush and Blackbirds which break the shell on a stone. Snails are a bit easier to find and easier to pick up, due to their shells, so inspect the undersides of objects and pick them off. Ground-feeding birds such as Thrushes and Blackbirds love them and like a boulder to smash them against.
Taken from: http://www.dgsgardening.btinternet.co.u
Jo Hanslip
June 2008
Images are at Photobucket:
Good, bad and bugly
Jo