1. Home
  2. Dermestes frischii Kugelann, 1792 (Kugelann, 1792)

Dermestes frischii Kugelann, 1792 (Kugelann, 1792)

Synonym(s) : 

  • Dermestes vulpinus Herbst, 1792 
  • Dermestes pollinctus Hope, 1834

Common names

  • Dermeste destructeur du cuir
  • Dermested beetle Hairy beetle
  • Escarabajo del cuero
  • Dornloser speckkäfer

Classification:

  • Order:  Coleoptera
  • Family:  Dermestidae
  • Genus:  Dermestes
  • Species:  frischii

Frequency index:

5
Posted by admin le
Back to the list

Overview

Most Dermestidae species of economic interest are found worldwide. Men have carried them around unintentionally for several thousand years, maybe even tens of thousands of years.
About 30 Dermestidae species (84 are recorded in France) are likely to infest our museums, heritage premises, warehouses, houses,… provided they can find the right food in them. 

The Dermestes genus alone is composed of more than a quarter of the species of the Dermestidae family in France, and though common in natural environments, it has the highest number of commensal species within the family. Dermestes (literally “skin-eaters”) are mostly carnivorous and necrophagous, and their voracious, often cannibal larvae feed on bodies and remains of animals (bones, feathers, hairs, skin, flesh,…), on dessicated insects, on pupae or nymphs (see “Infested Materials” chapter).

These insects are poor fliers, but they can spot food from very long distances (several hundred meters).
The Dermestes genus is easily recognizable thanks to its sturdy, elongate oval aspect and to the absence of a median ocellus on its forehead. Six more Dermestes species are described in fact-sheets in this website : D. Olivieri (= D. ater), D. carnivorus, D. lardarius, D. maculatus, D. peruvianus and D. undulatus.

Readers can refer to them for more information about those pests.
Hairy beetles are frequent and dreaded hosts of museums and libraries containing old books. They preferentially seek skins and leathers, but can also be particularly harmful to animal collections (insects, stuffed animals). They are also a scourge of the dried fish industry and are very common, especially in Asia.

D. frischii, like most other Dermestidae, is a very useful forensic entomology indicator for the scientific police, for its presence on a body can provide valuable chronological information for determining when death occurred. Specimens were found, along with other Dermestidae species, in Egyptian tombs dating back to around 3000 BC.
Together with D. carnivorus, D. maculatus and D. undulatus, Dermestes frischii belongs to the sub-genus Dermestinus, whose species are characterised by a dense hairiness on the ventral face of their abdomen which hides the cuticle from sight.

Recognition criteria

Adult

Size

6 to 9.5 mm.

Aspect    

Sturdy insect; egg-like, elongate shape
Body about 2.5-fold more in length than in width, covered with thick bristles of various colours and lengths which give them a slightly mottled aspect clearly visible in fresh individuals whose bristles have not been rubbed off.

The pronotum is rather massive and is about 1/3 of the elytra in length.
The antennae are rather short, they have 11 segments; the last 3 are wider and form a club.

The prothorax is ornate with a yellowish-white, golden-white pubescence on its front part and on its sides, more developed on the sides. The same kind of pubescence is also found on the top of the head, with a small tuft of silvery hairs on the inner border of the eye.

The elytra are covered with fine, flat, black bristles irregularly mixed with yellowish-white hairs.
Males differ from females by the presence of a tuft of black-brown hairs located in the middle of their fourth abdominal sternite.

Colour   

The dorsal face is very dark brown to black, legs and antennae are a lighter brown.
The ventral face of the abdomen is mostly ornate with a white or slightly pinkish-grey pubescence.
There are 2 black spots on the sides of each sternite ; in addition, the last sternite has a median blackish spot on its rear border, which does not extend to the front border of the sternite.

Larva


Size

They are 13 to 15 mm long when mature.

Aspect    

Elongate, narrow but sturdy, evenly narrower from front end to rear end. Hard, tough cuticle.

Body with sticking-up, reddish-brown hairs; some of them short and others (in smaller numbers) much longer. Hairiness a little thicker at the rear end.

On the 9th abdominal segment (the last one), presence of 2 sharp spikes called urogomphs. They are faintly bulbous at their base, get thinner and thinner and  end up sharp-pointed.

Seen in profile, these sharp ends are distinctly curved toward the insects’ backs (their front part).

Colour    

The whole body is very dark brown to black. The thorax and the abdomen have a longitudinal dorsal stripe made of light-coloured spots. That stripe is roughly the same width from thorax to pygidium, and it is clearly distinguishable from the rest of the body, which is blackish-brown.

Nota: The morphology or colour features mentioned here can only be used with old larvae, generally 12 mm long or more.

 

Development cycle

Adults are usually the ones that overwinter. They resume their activity in spring, but are particularly active in May and June, which is when they generally get into our premises, our heritage sites,…

Egg-laying starts in spring and can last till August or even later. In natural environments and in the south of France, active adults can be seen till October.
Females can lay 40 to more than 400 eggs over a 2-month period. Eggs are white and about 1.8 mm long. Fecundity depends on the water content of the food substrate: the higher the water content, the higher fecundity. Eggs are laid in small quantities and in several steps in the cracks of the material due to become the larvae’s food or in former galleries.

New-born larvae hatch 5 to 9 days after egg-laying. Optimal larval development requires temperatures between 30 and 33°C and cannot occur below 15°C or above 40°C. Five to 9 larval stages have been noted for this species. Larvae shy away from light, and they pretend to be dead by curling up in a ball and stopping any movement when they are disturbed.

Before reaching the last stage, larvae stop feeding, seek a shelter inside the infested material which has often been altered by the numerous galleries bored through it, and remain there in a pre-nymphosis stage. Actual nymphosis takes place about 2 weeks later and lasts about 10 days.

Similarly to many commensal insects, the total length of Dermestes frischi’s development cycle depends very much on ambient temperatures and on the nature of the larvae’s food substrate. It lasts about 1 month at 35°C (on dried fish) but can last up to 3 months at 20°C and much longer (6 to 9 months) in unfavourable conditions. Development is stopped if relative humidity is below 30%.

Adults rarely live more than 3 months. They shy away from light and strongly tend to hide in or under the substrate.
Although there is only one generation per year, Dermestes frischii populations can grow exponentially and be multiplied 30-fold each month in optimal development conditions.

Infected materials

Dermestes frischii exclusively feed on materials or products of animal origin.
The species is carnivorous and eats dessicated insects or fragments of dead animals (stuffed or not), horn, hairs, dried meat and fish, animal skins and their by-products (furs, book-bindings, parchment, leather) and even cheese.

A mere mouse or rat body can be the cause of a true infestation by hairy beetles. That is why it is necessary to keep all high-risk places clean.

In addition to the damage caused to the feeding stocks, various materials and substances cited above, let us mention that larvae can thread and bore galleries and tunnels through all kinds of materials (wood, cork, wood-panelling, plaster,…) while seeking for nymphosis sites.

Therefore they can indirectly cause serious damage to other materials than food.
We should stress that the development of this species is impossible in a strictly vegetal medium.

Geographical distribution

Nearly worldwide distribution