Stored Product Insects



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.
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.
Biscuit Beetle
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.
Flour Mite
A minute, slow-moving, white or pale-brown creature only a barely visible 0.5mm long, with eight legs. A pest of cereals and cereal products especially if they are damp.
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.
Brown House Moth
The commonest of the so-called clothes moths, with characteristic golden-bronze wings, flecked with black, folded flat along its back. The adult is about 8mm long and prefers to run rather than fly.
The related White Shouldered House Moth has mottled wings with a white head and “shoulders” where the wings join the body. Eggs are attached to fabric on which grubs will feed. The larvae are creamy-white caterpillars with brown heads.
They grow up to 18mm long, feeding on wool, hair, fur, feathers, cork or debris from food such as dried fruit or cereals, and are common scavengers in old birds’ nests, from which they may enter buildings.
The caterpillars spin silken cocoons in which they pupate. The life cycle takes several months to complete. Only the larval stage feeds, as a general scavenger as well as a textile pest.
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.
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.
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