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Attagenus unicolor (Brahm 1791)

Synonym(s) : 

Dermestes piceus Olivier, 1790

Common names

  • Attagène des tapis
  • Black carpet beetle
  • Escarabajo negro de las alfombras
  • Dunkler Pelzkäfer

Classification:

  • Order:  Coleoptera
  • Family:  Dermestidae
  • Genus:  Attagenus
  • Species:  unicolor

Frequency index:

5
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Overview

Species of the Attagenus genus are very close to those of the related genus Dermestes but they can easily be told from Dermestes thanks to the presence of an ocellus on their front and to their slightly smaller size.
In France, Attagenus are represented by about 15 species. Several of them are likely to be found in houses and heritage premises.
However, in France only the 2 species A. pellio and A. unicolor (Brahm) are important from an economic point of view as they can cause important damage; they are also the most frequent species.
Adults rarely live longer than 1 month. They are good fliers, and during the hottest months they visit flowers, although they feed little on their pollen and their nectar.

Their larvae have a polyphagous and necrophagous food diet; they mostly feed on dead insects, whereby the serious damage they can cause in insect collections.
They are also found in natural environments, where they infest birds’ or rodents’ nests where they eat feather, hair, or even dead animals’ fragments.
Imagos are strongly attracted by light and can easily be trapped with ultra-violet lamps.

Recognition criteria

Adult

Size

2.8 to 5 mm long.

Aspect    

Egg-like, elongate shape, round at the ends. Look like coffee beans when seen from a distance. A homogenous and inconspicuous dark pubescence covers the body and legs. Golden bristles scattered on the ventral face.
Rather small head, clearly protruding from the prothorax, eyes wide apart, short 11-articled antennae.
Transverse pronotum, twice as wide as long, and wider and wider toward the rear part. In males, the last antennal article is 2.8 to 3.4 times as long as the previous two put together.
It is about the same length as the length of those two articles put together in females.

Colour    

Reddish brown to black, the pronotum is usually slightly darker than the elytra. The males’ antennal club and the females’ last antennal article are darker than the rest of their antennae. Legs are red to reddish.

Larva

Size

6 mm at final development stages.

Aspect    

Look like small, curved, 11-segment worms entirely covered in a pubescence of tufts of long, dark, erect bristles.
The rear end has a characteristic tuft of bristles that is the same length as the last 6 abdominal segments put together

Colour    

Brownish yellow in the first place, larvae turn deep dark at the end of their development. Their head is brownish. Light-coloured spots are visible on the first segment near the head, and a few more on the next two segments.

Development cycle

Development lasts 9 to 30 months depending on ambient temperature and hygrometry conditions. Besides, depending on the nutrient richness of infested materials, larval development takes more or less time.
Mating usually occurs in natural environments on flowers, preferably flowers from the Apiaceae (Umbellifera) family (carrot, celery, coriander, fennel, parsley).
Females lay up to 50 eggs on an average (sometimes up to 100) in small cracks of the materials it is infesting, in natural environments as well as inside the premises it has settled into. In that latter case, eggs can be laid in hot air ducts or in plinths, in any case nearby food the larvae will need to develop. Incubation lasts 6 to 10 days. Larvae undergo 5 to 11 consecutive molts (20 maximum) over a 2- (in optimal conditions) to 24-month period. Then, after 6 to 24 days’ nymphosis, a perfect insect comes out.

 

Infected materials

Attagenus unicolor are particularly fond of insect collections where they can cause considerable damage. They are also frequently found in natural environments, especially in birds’ or animals’ (rodents’) nests where they feed on feather, hair and excrement debris.

Their food diet is remarkably varied: cereals and various types of flour, wheat, rice, certain dried fruit (raisins), peanuts, lining fabrics containing wool, cotton, rayon, Hessian, linen; furs, certain species of dried fish, powdered milk, spices (paprika), pet-food, carpets, clothes (stored in dark places), leather…

Larvae were even found living inside pianos and other music instruments. The species is frequently found indoors on insect bodies (diptera). It is therefore necessary to keep places clean.

Geographical distribution

Attagenus unicolor appears to be found worldwide: its presence is reported on all continents.