Linnaeus described this insect in 1758, it was in all probability already
cosmopolitan. The French called it the "cadelle" (which from the Latin catulus
means offspring) and this is the name by which it is commonly known at the
present time. It is known also as the "bread beetle" because of its habit
of cutting the silk bolting in flour-mill machinery. Hatch (1942) notes
in Europe the cadelle lives outdoors under bark and in rotten wood. Here
it is predacious on wood-feeding insects.
Originally an African species, this beetle
has now spread to all parts of the world. It is found particularly in
grain warehouses, silos and mills. The larvae live hidden away, feeding
on corn and flour , but also, to a certain extent predating on other insect
cadelle is believed by some entomologists to be a native of America, for
all species of the family Ostomidae are found in the New World. It is
one of the best known of the stored-grain pests, in part because it is
also a common "pantry pest" in the house, where adults and larvae feed
on cereals, breakfast foods, potatoes, shelled and unshelled nuts, or
fruit, and prefer to lay their eggs under the flaps of cartons. They can
gnaw through sacks and paper packages and wood, thus allowing other insects
access. Unlike the granary and rice weevils, they feed not only on whole
grains, but also on flour and a variety of other products, and are therefore
much more important as pantry pests.
cadelle may have been originally a predator under loose bark, as other
species of the family are today. It does attack the larvae of other grain-infesting
Plodia interpunctella and Oryzaephilus surinamensis.
Another peculiarity of this insect is its habit of burrowing into the
woodwork of grain bins or other wooden structures, sometimes causing them
to collapse. It may remain there for long periods in large numbers, only
to emerge and infest the next load of grain. Other grain pests may also
hide in its burrows.
shiny black adult is elongate, oblong, and flattened, and is one of the
largest of the grain-infesting beetles, being about 8 to 9mm long. The
prothorax, is distinctly separated from the rest of the body by a loose,
prominent joint, the
males can be distinguished from the females by the numerous and fine punctures
on the ventral side of the abdomen, whereas the punctures on the female
are less numerous and coarser.
The females lay about 1,000 eggs loosely in flour, grain, or other foodstuff.
Although the following experiment was interesting: Bond
and Monro (1954) reared the cadelle on oatmeal cultures containing moulds
or yeast. They found the female lays her eggs in clusters in the food
or packs them in crevices. One female produced a maximum of 3,581 eggs.
The eggs, laid in clusters of between 10 to 60 eggs in food materials,
hatch in about 10 days. The fleshy, white to greyish-white larva has a
black head and a black plate with two horny black projections at the tip
of the abdomen (see picture below) and the larvae may reach 3/4 inch in
length. The life cycle may be as short as 70 days, but it may be much
longer under conditions unfavourable to the insect's development. The
females generally live for a year, and have been kept alive for more than
of the larval period varies with the environment and may extend from 38
to 414 days. The cadelle may undergo from three to seven molts, the average
for this insect being four. The
larvae and adults are large and can go without food for 52 days (adults)
to 120 days (larvae). The larvae feed on a great variety of grains, as
well as on flour, meal, biscuits and bread, vegetables, dried fruits,
larva was found capable of destroying the germinating powers of 10,000
larvae, when attacking such grains as wheat and oats, usually confine
themselves to the embryo, this being the softests part.
Upon migrating from its food source in
order to pupate, it occurs accidentally in such unusual places as books,
balls of twine, carpet rolls, rugs and in bottles of milk.
The cadelle pupates in from eight to 25
days. In more temperate countries there may be two generations with a
partial third. It is believed there are three generations in tropical
insects are also a serious pest in tobacco factories. Here they occur
in bales of dry tobacco where it is claimed they bore into them in search
of insect larvae. According to Candura (1943), the young larvae will
feed on the tobacco, but will die unless they are able to feed on insects
too. The larvae require two to three years to develop in the tobacco
which they finally destroy through their borings. The larvae pupate
or hibernate by hollowing out a cell in the adjacent wood. Thus, they
may remain in the wood or empty bins for months and then emerge to reinfest
fresh grain placed in these bins. This woodboring habit of the larvae
has resulted in the pupal chamber being excavated in such curious places
as the corks of bottles and in books.
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