The Ptinidae family are closely related to the Anobiidae, and sometimes included in that family. Their natural habitats are bird and animal nests where they scavenge on debris. There are about twenty native British species, and several introduced species.
On the right is Ptinus tectus, the spider beetle, originally from Australia, it is a scavenger that will feed on just about anything in the house. In warehouses seeds and grain are attacked. It is also found in the U.S. and Canada. It does not bite or spread any diseases.
The antennae usually have 11 segments, and its body length is around 2 mm. It is usually brown/black.
The adults are supposed to resemble spiders - hence its common name. When the adult is disturbed it pretends to be dead.
Life cycle. The female lays about 100 eggs, either singly or in groups over a period of 5 weeks. The eggs are sticky, so soon become covered in debris, they measure 0.5 mm x 0.35 mm. The larvae are covered with fine hairs are cream-coloured and fleshy. When disturbed they roll up into a ball. They can bite through relatively tough materials such as sacks, cardboard, and cellophane. The lifecycle takes about three and a half months at room temperature.
Niptus hololeucus, left
This tiny beetle (adult length 2.6 - 4.6 mm) is covered with yellow hairs. It was introduced to the UK from Russia in 1838, and is now found worldwide.
There are 900 species of Bruchidae in Northern Europe, and about 12 species are native to the U. K. However many species have been introduced in imported food. They usually eat seed. Their antennae are thickened towards the tip.
On the left is Bruchus pisorum, the pea beetle. The larva of Bruchus pisorum eat only peas.
The adults feed on pollen and pea petals for a few days then mate. The female lays around 400 eggs singly, each on a separate pea pod. After about 10 days the egg hatches, and the larva tunnels through the pod wall into a pea where it feeds.
After 40 - 45 days it cuts an exit hole in the pea, but pupates inside. After about 10 days the adult emerges from the exit hole.
There is usually one generation per year. This beetle is also known as the pea weevil, but it is not a true weevil.
Above is Anthrenus flaviceps, a furniture and carpet beetle. Adults are hardy enough to live outside.
Commonly known as the carpet beetles, larder beetles and hide beetles. There are 850 species world wide, 50 European species and 40 British species.
The adults are covered with hair or scales, and the antennae are clubbed and can be drawn under the body with the legs. Most are scavengers, and some are pests.
The larvae are often called wooly bears. Dermestidae means "skin eater". Some of the pest species will eat both natural and synthetic fibres.
The adults often fall to the ground and feign death when disturbed. When the larvae are ready to pupate they will burrow into anything - even wood and lead.
Above is Attagenus pellio, the 2 spot carpet beetle, also known as the fur beetle. Adults are 3.5 - 6.0 mm long. It attacks skins, furs, textiles and entomological specimens.
Adults are dark brown to black with patches of white or yellowish hairs. Females lay 50 - 100 eggs on larval food, e.g. carpets, bird's nests. The larva are hairy with a tuft of long hairs on the last abdominal segment. They avoid light, and when disturbed play dead. The entire life cycle is anything from 6 months to 2 years.
On the right is Dermestes lardarus, another member of the Dermestidae family. It is commonly known as the larder beetle or the bacon beetle.
It is fairly easy to recognise as the top half of the elytra (wing cases) are covered in a wide band of cream, yellow or tan coloured hairs with dark spots, and the adult antennae are strongly clubbed.
Females can lay about 200 - 800 eggs in batches of 6 - 8 in their lifetime. The eggs are 2 mm long, and laid in crevices, or on or near food. The larva is covered in dark brown hairs, and favours dark places. They feed on ham, bacon other meats and cheese, in fact it will eat most animal substances; outdoors they can be found on carcases. The larva are usually found just before they pupate, as they leave their food and wander around to find a safe place. They often bore into wood, but can bore into lead and even tin. They will feign death if exposed suddenly to light. A fully grown larva is 10 - 15 mm long.
Once they have hatched into an adult they can be easy to find around windows as the try to escape outside to feed on their adult food of pollen. Adults are about 6 - 10 mm long.
The normal life cycle is 2 - 3 months, however this can be much longer as they can hibernate if the temperature falls. Nowadays they are less common in houses, and where they are found they will probably have been feeding on dead mice under floorboards, or dead birds in the chimney.