Australian Spider Beetles

Key Features

Adult Australian Spider Beetles (Ptinus tectus) are small oval or cylindrical insects with long legs resembling giant mites or small spiders. The head is often hidden when viewed from above. They are 2 - 3mm long with long filamentous antennae. As with all insects, the spider beetles possess only six legs, and it is the long antennae that resemble a fourth pair of legs.

Most Australian Spider Beetles are brownish-black with a large, globe-like abdomen and the prothorax (first segment behind the head) constricted at the base of the wing covers. Larvae are C-shaped or grub-like and cream-coloured with short legs. The segmented abdomen contains many long hairs.

Biology

The female lays about 100 opalescent, sticky eggs, singly or in small groups, over a period of 3 to 4 weeks. Food and debris adhere to the eggs. The fleshy larva (which can grow up to 3.4 mm long), covered with fine hairs, is strongly curved, cream coloured. Pupation takes place in a tough, spherical, thin-walled cocoon. The adult may remain in this cocoon as long as 3 weeks, after emergence and the total life cycle, from egg to the adult leaving the cocoon, can be as much as 95 days.

Distribution

This species arrived in Europe and the UK from Australia as recently as 1900, but it now abundant across the country. Spider beetles sometimes become prominent cereal pests in Canada and the northern United States. Some have been found quite active even during freezing weather.

Significance

Spider beetles are general scavengers. They feed on a variety of items, such as cereals, seeds, flour, meat, dried fruits and vegetables, fish food, dead insects, rodent droppings, old wood, cayenne pepper, roots, cocoa, sugar, drugs, and spices.

Common sites of infestation in the house include wall voids and drop ceilings, as the infestation usually originates in a birds nest. Spider beetles are primarily warehouse pests, attacking various seeds and certain whole grains, such as wheat, barley, rye, and flax, they can also destroy insect collections and damage stuffed animals. Also, serious infestations have been found in flour and feeds, such as bran shorts and meal preparations.

Control

The first step in managing an infestation is to find and remove the source of the infestation (Koehler 2003). Spider Beetles can feed and survive on even the smallest bits of spillage, so cleaning is a crucial part of controlling these pests. In large-scale infestations, fumigation (the treatment of the infested material via the application of toxic gas) may be appropriate.