Adults overwinter. They can live several months (6/7) ; in natural environments in the South of France, they are active from April to October. Oddly enough, we have very few precise biological data about Dermestes undulatus ; its development cycle appears to be very close to that of Dermestes lardarius, which is given below as a reminder :

The complete cycle lasts 6 to 9 weeks in optimal conditions, between 22 and 27°C with 65% relative humidity.
Fecundity is impossible below 15°C and above 30°C, but it is optimal when the food substrate is rich in nutrients and water.
Egg-laying starts as soon as early spring; females can lay more than a hundred eggs within up to 6 months.

They lay them in small groups (2 to 8/10) in the cracks of the infested substrate and in larval galleries. New-born larvae hatch about one week after egg-laying.

Larvae (like adults) are very brisk, they shy away from light and they pretend to be dead by curling up in a ball and stopping any movement when they are disturbed.

The number of larval stages required for their development depends on ambient temperatures and on food : it is 6 at 20°C and 8 at 27°C.

Before reaching the last stage, larvae stop feeding, seek a shelter or a cavity inside the infested material which has often been altered by the numerous galleries bored through it ; they remain there, immobile, in the pre-nymphosis stage.
Actual nymphosis takes place about 10 to 12 days later and lasts about 10 days.

Imagoes stay a few days in their cell before leaving it and taking flight to the outside world.
There can be 2 generations per year.

Similarly to many commensal insects, the total length of Dermestes undulatus's development cycle seems to depend very much on ambient temperatures and on the nature of the larvae’s food substrate.

Dermestes undulatus exclusively 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).

Its larvae can also be found in animal foodstuff warehouses, where it can grow at the expense of hams, sausages, various charcuterie delicatessens...

A mere mouse or rat body can be the cause of a true infestation.
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 products than food.

The species probably originated from Europe. It is commonly found in Western Europe and can be found as far as Siberia.

It tends to spread worldwide due to commercial trade and can also be found in Africa, North America and Asia.

Comment :

Among the other Dermestes species found in France (there are 22 of them) and more particularly those of economic interest, D.undulatus adults can easily be identified thanks to the following features taken together :

                                     - the elytra and the protonum are of different colours (see « Identification criteria » and photos),
                                     - the ventral face of the abdomen bears a white pubescence,
                                     - the abdominal sternites bear 2 lateral black spots,
                                     - the last sternite is almost entirely black but there are 2 isolated white spots next to the front border
                                       of the segment.

Old D.undulatus larvae can be told from the larvae of similar species thanks to the following features taken together:

                                     - the thorax and the abdomen bear a longitudinal reddish dorsal stripe.
                                     - the spiky ends of the urogromphs are at a right angle with the body axis, and slightly curved.

D.undulatus larvae are very similar to D.frischi and to D.maculatus larvae (see fact-sheets), but they have a distinctly more ruffled aspect. Urogromphs are slightly curved forward.