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Dermestes maculatus De Geer, 1774 

Synonym(s) : 

  • Dermestes marginatus Thunberg, 1781 
  • Dermestes vulpinus Fabricius, 1791 
  • Dermestes australis Dejean, 1821 
  • Dermestes elongatus Hope, 1834 
  • Dermestes truncatus Casey 1916

Common names

  • Dermeste des peaux
  • Hide beetle, Leather beetle
  • Dermeste zorruno

Classification:

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

Frequency index:

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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 that they can find the right food in them.

The Dermestes genus alone comprises 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).
Though brisk and quick walkers, 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. frischi, D. lardarius, D. peruvianus and D. undulatus. Readers can refer to them for more information about those pests.

Leather beetles, like almost all species of the Dermestes genus, are preferentially necrophagous. They are particularly feared in insect and animal collections, for they are likely to cause severe damage in insect boxes and stuffed animals, among other things.

These insects can also ruin dried fish and dried meat stocks, but above all, it is their larvae that cause the most considerable damage.
They are also considered as valued partners in certain natural history museums for « cleaning » animal skeletons meant to be exhibited in display rooms.

D. maculatus, 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.
It was found, along with other Dermestidae species, in Egyptian tombs dating back to around 3000 BC.

Together with D. carnivorus, D. frischi and D. undulatus, Dermestes maculatus 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.

Recognition criteria

Adult

Size   

6 to 10 mm.
 

Aspect    

Sturdy insect ; egg-like, elongate shape. The pronotum is massive and is 1/3 of the elytra in length.
Body about 2.5-fold more in length than in width and covered with flat, yellowish bristles.

The bristles are dense and thick on the sides of the thorax and form a wide golden stripe.
The same kind of pubescence is found on the top of the head and on the scutellum.
 
The antennae are short, they have 11 articles; the last 3 are wider and form a compact club.
The species is characterised by the presence of a small tooth at the end of the suture margin of each elytron.

Males differ from females by the presence of a reddish zone with a tuft of long red-brown hairs at its centre and located in the middle of their fourth abdominal sternite.
 

Colour   

The dorsal face is brown, more or less reddish, legs and antennae are a lighter brown.
The colour of this species and its pubescence are quite variable; the background colour can range from red brown to black or grey.
The ventral face of the abdomen is mostly ornate with a white or slightly chalk-white pubescence. There are 2 black spots on the side of each sternite; in addition, the last sternite has a median blackish spot that extends to its front and rear borders.

Larva

Size   

They are 14 to 16 mm long when mature.
 

Aspect    

Elongate, narrow but sturdy, evenly narrower from front end to rear end. Hard, tough cuticle. Body with sticking-up red-brown hairs, some of them short and others (in much smaller numbers) much longer.

On the 9th abdominal segment (the last one), presence of 2 sharp spikes called urogomphs. Seen in profile, these sharp ends are perpendicular to the body axis and slightly curved toward the front part.
 

Colour   

The whole body is dark brown. The thorax and the abdomen have a longitudinal dorsal stripe made of light-coloured spots. At the rear end, that dorsal stripe gets thinner so that the light-coloured spots can appear as isolated.

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

Development cycle

In natural environments, adults overwinter and 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, active adults can be seen till September. The development cycle lasts 4 to 8 weeks and depends a lot on ambient hygrometric conditions ; development is optimal between 30 and 35°C, and 70% relative humidity.

Fecundity depends on the food substrate and its water content. Females can lay more than 400 eggs in optimal conditions on dried meat, but only about 20 on rabbit's skin. The higher the water content, the higher fecundity is.
The number of larval stages required for the complete development of the insect depends on food, temperature and ambient relative humidity.

Thus, with 75% relative humidity, there are 6 molts at 35°C and 7 or up to 9 if temperature and/or relative humidity are lower. Eggs are white and about 2 mm long ; they 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 about one week after egg-laying.

Optimal larval development requires temperatures between 30 and 35°C and cannot occur below 15°C or above 40°C. 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 is often riddled with galleries, and remain there in a pre-nymphosis stage.

Actual nymphosis takes place about 2 weeks later and lasts about 10 days. Imagoes can live several months (2 to 6) ; they shy away from light and strongly tend to hide in or under the substrate. The species is univoltine, which means that there is only one generation per year.

Infected materials

Dermestes maculatus preferentially feeds on materials or products of animal origin. The species is carnivorous and necrophagous 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, parchments, leather) and even cheese.

It can occasionally grow at the expense of vegetal flours (copra, cereal). A mere mouse or rat body can be the cause of a true infestation ; that is why it is recommended 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. That insect can also cause serious damage in hen-houses where it damages insulation panels by boring through them. Leather beetles have also been reported to infest bee-hives in South-East Asia.

Geographical distribution

Leather beetles quite probably originated from Eurasia.

They can be found worldwide, except in very cold regions. They are particularly common in the Mediterranean area.