Pests from A to Z
Beetles
Beetle Larvae
Mealworm
A term applied to the larvae of the three species of Mealworm Beetle. Adult beetles are about 15mm long, dark brown and scavenge in damp larders or down in basement food stores. They frequently breed in old birds’ nests. The larvae are large (up to 28mm) and pale yellow in colour, with clearly defined segments along the body. They are sold in many pet shops as food for fish and reptiles.
Woodworm
A term used for the destructive larvae of the Common Furniture Beetle.
First sign of woodworm is the appearance of neat round holes, 2mm across, in wooden surfaces, often accompanied by tiny piles of wood dust beneath them. Fresh holes show clean white wood inside. The holes are made by emerging adult beetles, immature grubs may still be tunnelling away inside the wood.
The adult Furniture Beetle is a small brown insect 3mm to 6mm long which flies quite readily. It lays eggs on rough, unpolished wood and the grubs bore straight into the wood – leaving no trace until they emerge as beetles three years or so later, usually between May and September.
Woodworm is frequently introduced into the house in second-hand furniture, tea chests or wicker-work; but the beetles are quite capable of flying in through a window from nearby dead branches of trees. They may then attack floorboards, joinery and, more seriously, structural timbers such as rafters and joists.
Other woodborers include: Death Watch Beetle, which infests only large old hardwood beams; the House Longhorn, confined – at least for the moment – to North West Surrey; Powder Post Beetle which needs a diet of starch in certain hardwoods, and woodboring weevils, which are associated with wet rot and die out when it is treated.
Biscuit Beetles
These are closely related to the Common Furniture Beetle or wood-worm. They are small reddish-brown insects, only about 3mm long, which attack stored foods in domestic larders. Flour, biscuits, cake mixes, cereals, spices, meat and soup powders will attract them, and they have even been found thriving on such poisonous substances as strychnine, belladonna and aconite – hence the beetle’s American name; Drug Store Beetle.
They have been known to penetrate tin foil and lead, and have even bored through a shelf-full of books. The white larvae are very small and quite active when they hatch. They feed and grow for about four months before knitting themselves cocoons of food particles in which to pupate.
Carpet Beetles
The larvae (known as “woolly bears”) of these small, oval beetles have outstripped the clothes moths as the major British textile pest. The Variegated Carpet Beetle is 2 to 4mm long, like a small, mottled brown, grey and cream ladybird. The related Fur Beetle is black with one spot on each wing case, and there is a rarer Black Carpet Beetle. The larvae are small (about 4mm long), covered in brown hairs, and tend to roll up when disturbed. As they grow, they moult – and the old cast-off skins may be the first sign of infestation. Adults are often seen in April, May and June, seeking egg-laying sites; and the grubs are most active in October before they hibernate.
The adult Carpet Beetle feeds only on pollen and nectar of garden flowers but lays its eggs in old birds’ nests, felt, fabric or accumulated fluff in buildings. It is the larvae from these eggs that do the damage. They feed on feathers, fur, hair, or wool and tend to wander along the pipes from roofs into airing cupboards – which house the clothes and blankets which constitute the food.
The life cycle takes about a year, and the grubs can survive starvation in hard times for several months. Carpet beetle damage consists of fairly well-defined round holes along the seams of fabric where the grubs bite through the thread.
Death Watch Beetle
A woodboring beetle whose grubs eat old hardwood structural timbers. Practically a status symbol for owners of stately homes in which the beetle family has probably lived since they were built. Adults rarely fly, so infestations are diminishing as old buildings are either treated or demolished. The death watch beetle does not like modern softwood house timbers.
Grubs live up to ten years inside timber, emerging as mottled grey/brown beetles about 7mm long, through exit holes about 4mm in diameter. When adult, they produce a rapid tapping sound by beating their heads against the wood as a mating call.
Flour Beetles
Small reddish-brown beetles about 3-4mm long that feed on flour and cereal debris in warm buildings. May be accidentally introduced into the larder in packaging or in the ingredients themselves. Commonest species are the Rust Red Flour Beetle and the Confused Flour Beetle (which in turn is often confused with the Rust Red Flour Beetle).
May produce five generations in a year and adults can live for over a year. The eggs stick to flour particles and the yellow-brown larvae, about 6mm long, crawl about very actively.
Fungus Beetles
A general term for various very small (3mm) beetles that feed on moulds in ill-ventilated, damp buildings.
Fur Beetles
An oval black beetle 4-6mm long with a white spot on each wing case. Grubs are about 6mm long, with a tuft of golden hairs on the end of their bodies. They can often be detected by their cast-off skins as they moult. Grubs feed on fur, hair, skins, feathers and wool and may damage upholstery.
Furniture Beetle
A small brown beetle, 2.5-5mm long, that is the adult form of woodworm. Emerges from infested wood between May and September, especially in June and July, leaving round exit holes 1-2mm in diameter.
Ground Beetles
Various large black or violet beetles that occasionally wander in from the garden or emerge from under door-mats. The larger ones grow up to 25mm long.
They are harmless and no treatment is necessary.
Larder Beetle
A fairly large (7-10mm) oval beetle, almost black but with a distinct pale band across the front of the wing-cases. The larvae are white after first hatching, but turn brown and are covered with tufts of bristly hair. They grow to 10-12mm long and occasionally tunnel into soft wood to pupate. The life cycle takes about three months.
Both beetle and larvae are scavengers, feeding on scraps of food – especially ham, bacon or cheese, or on dead mice or birds. They often enter houses from old birds’ nests. One of a family called the Dermestid beetles, meaning “skin eaters”. Related species include the dark-brown Leather Beetle and the very similar Dermestes haemorrhoidalis, which perhaps not surprisingly has no English name.
Longhorn Beetle
See Woodworm
Plaster Beetle
Originally descended from the wild Rock Dove, a cliff-face dweller, these birds find the next best thing is a block of flats, a bit of Victorian Gothic architecture or a railway arch. In the absence of natural predators, birds which fall sick survive to infect healthy ones with ornithosis and other diseases, some of which can be transmissible to man. Their accumulated droppings are also sources of disease.
Spider Beetles
A group of beetles with globular abdomens and fairly long legs, superficially resembling small spiders, 3-4mm long.
General scavengers of all sorts of animal and vegetable debris and stored food, and frequently associated with old birds’ nests. The Golden Spider Beetle (below) is covered with golden hairs whilst the Globular
Spider Beetle is a shiny, dark brown colour.
The Australian Spider Beetle is by far the commonest species. Adults may feign death when disturbed. The female lays up to 1,000 eggs, which are sticky. The fleshy larvae roll up when disturbed but when ready to pupate wander about and may get into cracks and crevices in floors or shelves.
Weevils
A term frequently misused to describe beetles in general, but actually applicable only to a distinctive group of beetles with long, pointed “snouts” which they use for boring into whole grains, hard processed cereals such as pasta, and timber.
Mainly pests of stored cereals on farms.
Wharf Borer
A brown beetle, about 1cm long, with pronounced antennae and a tendency to emerge from damp basements and fly about near rivers or estuaries in early summer.
The grubs live in very decayed wet timber such as old jetties or wooden piles. Buildings built over old bombed sites with timbers buried under them are sometimes invaded by these beetles for a few odd days.
Wooly Bears
The small hairy grubs of the carpet beetles and fur beetles.
