Beetles are small Coleoptera belonging to the family of Dermestidae (skin eaters). They are widespread but prefer warm countries, hence their subtropical origin. They are able to digest keratin and feed on plant- and animal-based products. These insects are parasites in warehouses, homes, museums and any other places where the foods that they eat are present. They are the most harmful insects for textiles. They are found in non-tropical countries thanks to central heating that allows them to reproduce without constraints. The species most commonly found in Canadian households are the varied carpet beetle (Anthrenus verbasci) and the furniture carpet beetle (Anthrenus flavipes).
Varied carpet beetles (Anthrenus verbasci)
The adult varied carpet beetle measures approximately 3 mm and can live from two to six weeks. Its oval, convex body is black with brown, white and yellow microscopic scales. The larva is four to five millimetres in length and has a hairy body with alternating light brown and dark brown stripes. The tip of its abdomen is characterized by three tuffs of golden hair that it uses as a defense against predators. The larva of this species is easily identifiable by its shape – narrower in front and wider in back. It can remain in the larval stage for up to two years.
|| Anthrenus verbasci adult stage
||Anthrenus verbasci larval stage
Furniture carpet beetles (Anthrenus flavipes)
The adult of this species resembles the varied carpet beetle, but is slightly bigger and rounder, and lives longer (four to eight weeks). It can reach 4.8 mm in length. The larval colour varies from white, chestnut or light brown, depending on its diet. In addition to being covered with brown hairs, the larva’s shape is wider in front and narrower in back, unlike the A. verbasci species.
|| Anthrenus flavipes adult stage
||Anthrenus flavipes larval stage
Comparative table of A. verbasci & A. flavipes species
||Eggs laid (No.)
||Hatching time (days)
||Larval stage duration (days)
||Pupal stage duration (days)
||10 to 20
||220 to 630
||10 to 13
||9 to 16
||70 to 94
||14 to 17
Biology and behaviour
Beetle larvae are common household pests. Their development time varies with temperature, humidity and food availability. The adults feed on pollen and nectar, mainly from umbelliferous and compound plants. Females lay their eggs near sources of food in crevices and dark and sheltered places. Once the larva emerges from the egg, and until it becomes an adult, it lives in the dark and feeds on organic materials such as dust, cotton, wool, hair, animal fur and feathers, dandruff, dead insects and animals, carpets, fur, etc. The larvae alone are responsible for the damage caused to some furniture and household items.
Places where they can be seen
Unlike the adults, who enjoy the outdoors, the larvae prefer dark and quiet places such as the underside of rugs, cupboards, closets, baseboards, drawers, etc. The larvae are especially visible in the fall, when they are on the lookout for food and hibernating sites. The main infestation reservoirs are abandoned bird, rodent and insect nests, as well as animal cadavers. Insect collections, stuffed animals, and books are also vulnerable to attack, making beetles a major potential pest in museums and libraries. Cut flowers can also serve as a means of transporting adult insects into the house.
Infestations can be prevented by periodically inspecting the places beetles prefer and adopting good cleaning habits, including regular airing of enclosed places (cupboards, drawers, etc.). Sealing cracks and fissures can also prove to be a prevention method. Placing naphthalene balls (moth balls) in enclosed spaces can help keep beetles away, but is not a very effective method. It is also recommended that you remove abandoned bird and insect nests from buildings. You should also examine cut flowers for the presence of these adult insects before taking them into the house.
Damage is caused by the larvae and is characterized by clean, irregular holes in textiles. Traces of exuviate (old larva moult) and excrement – the size of a grain of salt – indicate places where they have been. Unlike mites, beetles leave no web. Be especially vigilant whenever you see adults near windows or buildings.
Beetle control can be fairly hard work given their ability to live in the dark and the large area they can inhabit. In the event of an infestation, the first thing to do is to find the source and eliminate it. Vacuum regularly thereafter and, obviously, dispose of the bag. Any infested object can be sterilized using cold (two weeks in the freezer) or heat (30 minutes at 70°C). Any clothing, sheets, curtains or upholstery showing signs of infestation or larval damage should be dry-cleaned. Applying an insecticide rug shampoo can be effective in eliminating the eggs laid by beetles.
In extensive infestation cases, it may be necessary to call in exterminators specializing in pest control. They will spread a contact insecticide. In major cases, atmospheric treatment will be required in the contaminated rooms. Placing sticky traps scented with pheromones (reconstituted female sexual hormones) can also help reduce beetle populations. Such traps are also of use in identifying the extent of the infestation and determining where the insects are coming from. They can also be used in combination with other treatments. Sticky traps without pheromones can also be installed around windows.
Other interesting facts
Larva exuviate is often confused with living larva, giving the impression that the infestation is greater than it actually is. The adult beetles, like lady bugs, belong to the order Coleoptera and are often taken to be tiny lady bugs, which is far from being the case. The hair of the larvae can also produce allergic skin reactions, so it is best not to handle them.