How to control silverfish
Recent years have seen a rise in silverfish infestations and as they can often be hard to control due to behaviour and habitat. We hear from a global industry expert, who gives his advice on identification, control, and research into new bait formulations.
Dr. Volker Gutsmann, Envu, Monheim, explains to allow effective control of this growing pest, it is importnat to be well versed in distinguishing between the many different species.
“Often infestations of “silverfish” turn out to be infestations of the Grey silverfish or Paper fish (Ctenolepisma longicaudata) and not the Common silverfish (Lepisma saccharina),” points out Dr Gutsmann.
“Both of these species differ in appearance. The common silverfish body is 10 mm long, silvery in colour, featuring two long antennae, a tail that consists of two cerci and one terminal filament. The Grey silverfish on the other hand is larger, measuring about 13-15 mm body length, grey-ish in colour and with scales and tail elements that are much longer than the silverfish,” he says.
Dr Gutsmann explains that along with differences in appearance both species reside in different habitats.
“Common silverfish like an environment of around 70% relative humidity whereas Grey silverfish can thrive in drier conditions and can be regarded as a nuisance to the homeowner as they can start to destroy paper-based items.
“Because of this, the Common silverfish is mainly a problem in bathrooms, kitchens, and toilets and in areas that suffer water leakages. The Grey silverfish, however, is also a guest in living rooms, public areas and storage rooms, where conditions tend to be drier,” he says.
Controlling the pest
“Common silverfish can be relatively easily controlled by improving the humidity in certain locations. Improved ventilation or the repair of dripping water fittings may be enough to get rid of this species.
“However, these measures may not be enough for Grey silverfish as this insect survives well in normal humidity levels,” he adds.
“Large infestations of Grey silverfish that begin to show damage to household contents need to be controlled by a pest controller.
“Unfortunately, the control of Grey silverfish is not as straight forward as the control of other crawling insects such as cockroaches.”
Dr Gutsmann explains that this is due to the variety of habitats.
“Locations where Grey silverfish live and hide can be anywhere – floorboards, skirting boards, behind boxes, pictures, books and furniture.
“To deliver a liquid application to all these different types of potential harborages is often impossible,” he says.
“Secondly, bait cannot be applied in the usual pattern, like that in cockroach control. Although there is evidence that both silverfish species feed on cockroach bait, they do not actively ‘search’ for food like cockroaches do,” he adds.
“It seems that silverfish accidently get in contact to bait and if they ‘stumble upon’ it, they will feed, but they aren’t attracted to a bait spot over a distance. Besides this fact, there is only one registered bait product for controlling Common silverfish or Grey silverfishin the EU,” says Dr Gutsmann.
Field trials against silverfish and Grey silverfish
Dr Gutsmann discusses recent trials into a new bait formulation to combat Common silverfish and Grey silverfish.
These trials were conducted with Maxforce® Platin (clothianidin), the first ever cockroach bait to have Common silverfish and Grey silverfish on the label.
“The first trial was conducted in the Netherlands by the urban entomology expert centre KAD. Four properties, all 20-year-old semi-detached houses with a living area of 110 - 140 m² were infested with the Grey silverfish.
“Inhabitants reported sightings of insects in all rooms on the ground floor and in bathrooms and toilets in the upper floor. Infestation levels were quantified in two ways prior to treatment: by visual inspection and using live traps.
