The female Australian spider beetle may produce 120 or more eggs over 3-4 weeks in
early summer. They are laid either singly or in batches and, being sticky, will adhere
to the substrate. At 20-25'C the eggs hatch in 3-16 days, giving larvae which are
fleshy, curved, covered with fine hairs and relatively immobile. although they will
rapidly curl up when disturbed.
Development takes at least 6 weeks, during which time the larvae moult 4 or 5 times.
When mature, they wander in search of a pupation site where they will spin a cocoon
cell in which to pupate. These cocoons are often found on the outside of cartons
through which the larvae have bored. Adults emerge after 20-30 days and will live
for as long as 12 months. If disturbed they will feign death. The full life-cycle
takes 3-6 months, depending upon ambient conditions, and can take place in a temperature
range of 5-28'C. The life-cycle of the Golden spider beetle resembles that of the
Australian species. The eggs hatch in 11 -30 days at 1 5-20'C, the larvae live for
150-250 days and pupation takes 18-26 days, after which the adults live for up to
Gibbium psylloides again has a similar life-c, to the Australian and Golden spider
beetles the adults are particularly long-lived, surviving for up to 1 1/2 years.
The optimum temperature for development, which can take place within the range 20-35'C,
is 33'C, when it takes about 45 days.
Gregarious and nocturnal, they spend the day in cracks and crevices amongst packaging
and the fabric of the store. Consequently they can thrive in old buildings where
they find many harbourages.