Charles McClintock of Sumitomo Chemical Australia explains why carpet beetles pose a threat to more than just your clients’ floor coverings.
Despite their name, carpet beetles don’t just target floor coverings. Their diet can be varied but their presence (and the damage they cause) often go undetected until large numbers of beetles are found around windows trying to get out. As with all pest control, knowing your enemy helps determine the best treatment and control strategies.
There are a number of carpet beetle species, with perhaps the most common being the variegated carpet beetle, Anthrenus verbasci, which has a mottled colouration and is around 2-3mm long (main picture, above). Other carpet beetles would include the larger black carpet beetle, Attagenus unicolor (more elongated and 3-5mm long) and the Australian carpet beetle, Anthrenocerus australis, which is the only native carpet beetle (similar to the variegated carpet beetle).
The key aspect of adult beetle behaviour is that the adults eat flower pollen and mostly live outdoors. They only come inside looking for a suitable site to lay their eggs. The beetles that are found around windows are adults, including newly hatched adults, trying to get back outside.
The adults look to lay their eggs on any animal-based materials, so woollen carpets and fabrics are a particular target. However, they will also target silk, fur and feathers. They often feed on the surface of preferred materials leaving threadbare spots and irregular holes. However, their presence can be difficult to detect as they will often feed around the edges and underside of carpets and in the folds of garments – an inspection needs to be very thorough.
Apart from damage, pest managers need to keep an eye out for bears – woolly bears – the common name given to carpet beetle larvae. These hairy larvae are slow moving and with a significant infestation, a number of spent skins will also be visible. Be careful handling any larvae as the hairs can break of causing an allergic reaction in some people.
Although woollen fabrics may be the most common target, they will attack a range of animal materials and can quite easily survive o the lint, hair and debris in floorboards and vents. If the source of the infestation cannot be located, also check the roof void and sub-floor as the larvae will happily eat animal carcasses and dead insects.
When carrying out a treatment for carpet beetles, the first step is to identify the source of the infestation. Ideally the source should be removed and thrown out. If that is not possible, as in the case of fitted carpets, the infested area should be vacuumed thoroughly and the contents of the vacuum bag disposed of. Treatment of any infested carpets with a quality insecticide such as Sumiguard will eliminate the infestation and provide continued protection against further infestation for several months. For spot treatments, or to treat cracks and crevices, Sumiblast aerosol with its flexible nozzle is a high performing and convenient option.
However, with a ready supply of new adults outside trying to get in, especially if there are flowerbeds immediately adjacent to the house, homeowners should be on guard for future infestations. Good housekeeping is the name of the game and they should be encouraged to vacuum thoroughly and regularly as well as pack away out of season clothing in sealed bags. Removing flowerbeds from the immediate house perimeter will help reduce adult invaders, but if this is not welcome, keeping windows closed or using well-fitting insect screens will do the job.
Although the adults have their peak emergence in spring and summer, with carpet beetles capable of several generations a year and the larvae taking between two and nine months to develop, an infestation can get quickly out of hand. It is perhaps a good idea to keep an eye out for carpet beetles on any general pest service.