[5] _Attagenus piceus_ Oliv.
The black carpet beetle derives its common name from the black,
unadorned color of the adult. Its larva is reddish or golden brown,
long and slender, with a characteristic tuft of long hairs at the end
of its body. It curls up and "plays 'possum" when disturbed. A glance
at Figure 5 will be sufficient for the identification of this unique
carpet-beetle larva.
[Illustration: Fig. 4.--Black carpet beetle: Dorsal view of adult
beetle. Greatly enlarged.]
Widespread in Europe and Asia, it first attracted attention in America
in 1854. Since then it has become widely distributed throughout the
United States, often being the most injurious of the carpet beetles,
especially in the more southern States. It is the carpet beetle most
commonly referred by housewives to the department for identification.
It feeds upon household fabrics of wool, feathers, fur, hair, and silk,
and also upon cereals and cereal products, seeds, and dried animal
remains, hence has many opportunities for existence in warehouses and
barns as well as in houses.
=The adult.=--The adult of the black carpet beetle is small, oval, and
black, as shown in Figure 4. The adults are present in abundance only
during the early summer. In a steam-heated building at Washington, D.
C, large numbers of adults were present late in April and during May,
but became rather scarce during the first part of June, although single
adults were found as late as early in July. The adult flies readily and
is often seen crawling on window panes and screens. It is during the
adult stage that the black carpet beetle spreads most easily from house
to house.
The female beetle lays small, white, fragile eggs upon fabrics, in
floor cracks, or in any sheltered spot near its food. The length of
life of the parent insect ranges from 3 to 35 days during April, May,
and June. Seldom are adults found later than July, except in very warm
storage houses.
=The egg.=--The fragile white eggs are very seldom seen, and hatch in
warm weather in about 6 to 10 days.
[Illustration: Fig. 5.--Black carpet beetle: Larval skin showing the
typical shape of the larva and the long tuft of bristles at the end of
the body. Greatly enlarged.]
=The larva.=--The golden brown larva, with short, stiff body hairs,
and its long tuft of hairs at the end of the body (Fig. 5), attains a
length of one-fourth of an inch, exclusive of the tuft of hair at the
end of the body. When first hatched it is almost microscopic in size,
but increases rapidly under favorable food and climatic conditions.
As it grows it sheds its skin from five to eleven times, and possibly
oftener. This is of interest, for frequently the cast skins are
mistaken for the insect itself, thus unnecessarily alarming the
housewife concerning the abundance of this carpet beetle. It required
approximately one year for larvæ to become fully grown when fed upon
casein. Larvæ hatching during early June and fed upon casein became
full grown and transformed to the adult stage during the following
April, May, and June. Larvæ fed upon woolen cloth and silk and flour
and meal were still only partially grown at the end of one year,
indicating that the black carpet beetle may require two years for its
development. In India it has been found that certain of these larvæ may
require from one to three years for growth.
[Illustration: Fig. 6.--Black carpet beetle: Ventral view of pupa.
Greatly enlarged.]
=The pupa.=--In the pupa stage the insect is white, clothed with fine
white hairs (Fig. 6), and helpless. The pupa stage continues from 6 to
16 days during early summer at Washington, D. C, and is seldom found at
any other season of the year.
=Seasonal history.=--Since the greater part of the life cycle is passed
in the larva stage, the facts previously mentioned indicate that the
black carpet beetle may have only one generation each year, although
it may require two or three years for the same development. From the
observation of the writer, made in houses, warehouses, and in the
laboratory at Washington, there seems little doubt that a very large
percentage of the insects have one generation each year. Farther north,
or under less favorable climatic and food conditions, a generation may
require two or even three years. At any rate, the adults are on the
wing during early summer and the eggs for new infestations are laid
then.
[Illustration: Fig. 7.--The varied carpet beetle: Dorsal view. Greatly
enlarged.]