species arrived in Europe and the UK from Australia as recently as 1900,
but it now common more or less everywhere.
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. Larvae cause a typical "scarring" of
the wood in buildings in the formation of pupal cells prior to pupation.
Spider beetles sometimes become prominent cereal pests in Canada and the
northern United States. Some have been found quite active even during
freezing weather. They do not bite or sting humans or pets, spread diseases,
or feed on or damage the house or furniture, but are a very common pest
in the home.
spider beetles are minute oval or cylindrical insects with long legs resembling
giant mites or small spiders. The head is often hidden when viewed from
above. They are 1/16 to 3/16 inch long with long filamentous antennae
(usually 11 segmented) arising on the front of the head close together
at the base. Most 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.
Cycle and Habits:
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 1/8 inch long), covered with fine hairs,
is strongly curved, cream coloured and rolls up into a tight ball when
disturbed. It can chew its way through sacking, cellophane, or cardboard,
and can hollow out a chamber in adjacent woodwork when making a place
in which to pupate. Pupation takes place in a tough, spherical, thin-walled
cocoon. The adult may remain in this cocoon as long as 3 weeks after emergence
(Hickin, 1964). Howe (1943) found that at 21°C (70°F) and 70% relative
humidity, the eggs hatched in 8.6 days; the 3 larval instars required
59.9 days; the pupal stage, 15.9 days; the pre-emergence period (adult
in cocoon), 9.5 days; and the total life cycle, from egg to the adult
leaving the cocoon, 93.9 days.
often bore into wood or cardboard boxes to overwinter in the pupal cell
with actual pupation occurring the following spring. Some spider beetles
can remain active during the cold months, especially in older buildings
where sources of food have accumulated. Spider beetles may become pests
in homes, warehouses, grain mills, museums, etc. They are attracted to
moisture, excrement, and abandoned animal nests.
treat a roof space the easiest way is with smoke generators (see the
Cluster Fly Page). To treat the rest of the house,
if these little beasties have come down out of the roof space, a regular
spray treatment should be carried out to wall/floor junctions with a
residual insecticide over a period of about three months. Remember,
spray kills the adults and the larvae but it doesn't kill the egg or
the pupae, so the treatment has to be carried out over a period of time
so that it gives the aggs and pupae a chance to become larvae or adults
and thus be susceptible to the spray.
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