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.
Above 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, above, (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.
Above 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.
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