If you've never heard of a silverfish, an insect also sometimes called a firebrat, you've probably seen one. This common insect earns its name due to its resemblance to an ancient, fish-like sea creature. While this insect isn't directly harmful to people, it can be destructive to items within a home or business.
What does a silverfish look like?
With a slim, segmented, metallic body and long antennae and appendages, a silverfish can look like something straight out of prehistoric times. And that's not too far off – the silverfish and its predecessors are some of the earliest known insects. Scientists estimate that the silverfish family dates back over 400 million years, before even dinosaurs.
Adult silverfish can be anywhere from a dark grayish-brown to metallic gray in color and average ½ inch to 1 inch in length. A young silverfish looks similar to an adult, but is smaller and lighter in color, often appearing nearly translucent or white.
A silverfish has two long antennae that extend from its head. It also has three appendages that extend from its tail. The insect uses both its antennae and these tail appendages for navigating its environment.
Silverfish, like all arthropods, go through a molting process as they grow. Unlike many other insects that molt, silverfish continue molting as adults. This molting process can leave cast skins and scales behind, which can be an allergen for some people.
How do silverfish reproduce?
Silverfish undergo a complex mating ritual, where a male and female have three encounters. First, they stand head to head, touching antennae. Then, they retreat. They return to this position, then the male runs away, pursued by the female. In the final phase, they stand head to tail, while the male vibrates. Finally, the male lays a spermatophore, which is then picked up by the female and used to fertilize her eggs.
The female will lay approximately 20 to 60 eggs in a crack or crevice. These small, white eggs will hatch in anywhere from two weeks to two months, dependent on environmental conditions.
A silverfish can live as long as three years, although this is unlikely in most active homes or businesses where they can be detected and treated.
What is an ideal environment for silverfish?
Silverfish thrive in moist, humid areas of a building or home similar to their natural soil-based outdoor environment. For these reasons, homeowners and pest management professionals may often find them in bathrooms, kitchens, basements, or areas of a home or building where water heaters or other electrical equipment is found.
The silverfish diet is a relatively simple one – they prefer starchy carbohydrates. In a home or building, books and cardboard are a favorite food of choice because of the dried, starchy paper and carbohydrate-based glue used in bindings.
However, a silverfish will also feed on crumbs and other foods humans leave behind, photos, wallpaper (particularly the adhesive used to adhere it to the wall), carpet, and even clothing. These insects will also consume skin and hair that humans shed, as well as other dead insects.
Any areas where stored products and/or sanitation issues are present and there is some humidity could be ripe for a silverfish infestation.
What are the signs of an infestation?
Many people may be unaware that they have a silverfish problem because these small, secretive insects tend to stay out of sight. They are nocturnal and don't move about as much during the day.
A homeowner or business owner may first discover they have a silverfish problem when they find a dead insect wedged within the pages of a book, in a light fixture, or in a cabinet in the kitchen or bathroom. However, living silverfish may also dart out from undisturbed areas when items are moved, surprising unsuspecting people.
A silverfish will leave behind some tell-tale signs of their presence, including feeding marks, which may look like irregular chewed holes in paper products. They can also leave behind metallic-colored smudge marks where they rub against items and small, black pepper-like feces. If silverfish are attacking clothing, they may leave behind small holes or yellow stains where they have fed.
How do I resolve a silverfish problem?
Pest management professionals may find that they need to use a multi-layer strategy to tackle a silverfish problem. This often takes significant customer cooperation, so it's important to be able to talk with your customers about how silverfish behave and the conditions that attract them and enable their survival.
Monitor. First, speak with your customers about where they are seeing the problem and use monitors to assess the issue. A sure sign that you're close to a silverfish habitat is when you identify nymphs on the monitoring device.
Identify the food source. If you can identify and remove the food source, you're headed in the right direction toward resolving a silverfish issue. This can be difficult because some food sources may be items valued by your customers, such as books or photographs. In these cases, ask your customer to place the suspected items in a sealed plastic container. The customer may be able to relocate items to a new area after the pest issue has been resolved.
Correct the environment. Successful silverfish populations require adequate humidity to prevent the insects from desiccating due to a lack of moisture. Encouraging customers with recurring silverfish issues to use a dehumidifier may help reduce the likelihood of problems in the future.
Chemical treatment. Silverfish can be treated using pesticide applications. Pest management professionals can consider the following tactics:
- Bait. There are a variety of bait products available for silverfish that mimic their preferred natural food source and will eliminate all feeding stages of the insect.
- Harborage treatment. Make insecticide dust or liquid residual applications with suspension concentrate or a micro-encapsulated product to the harborage and around the harborage entrance – in this case, cracks, crevices, and voids.
- Targeted use of controlled release products. Unoccupied areas can also be treated with a controlled release product, such as a slow-release insecticide vapor, often available in pellet formulation or impregnated into plastic strips. Care should be taken where applied: always read and follow label directions prior to any pesticide application.
With an understanding of these unique pests, the right tools, and the right approach, a skilled pest management professional will be able to resolve a silverfish problem with ease. Target Specialty Products is pleased to offer our customers a range of treatment products and monitoring tools that can help in this effort. If you're struggling with silverfish, talk to your Target Specialty Products account representative about the products that are right for your customers.
