NPIPM:Thysanura
Authors: Ashley Mueller, Buyung Hadi
Identification
Fully-grown silverfish and firebrats about 1/4 to 3/4 inches long, and they do not have wings. Their flattened, elongated bodies are carrot-shaped, thick at the front and tapering towards the back end. They are silvery to brown-black in color with long antennae and three tail-like projections. They are common in areas of high humidity, such as basements and bathrooms; firebrats are more common in areas with high humidity and temperatures above 90F degrees like heating pipes and furnaces. When disturbed, silverfish and firebrats can move very quickly.
Habitat
The natural habitat for silverfish and firebrats is outdoors in high-moisture areas, but they are able to move into homes and buildings. They can be brought indoors with materials that have been stored in infested areas. They are unable to climb smooth vertical surfaces, so they may be found trapped in bathtubs and sinks, often near the drain. However, they do not emerge from drains.
Silverfish and firebrats feed on a variety of materials such as flour, paper and even glue. Generally they prefer to feed on products that are high in protein, sugar, or starch. When they find a preferable food source, they will generally not stray far from it, although they can survive for months without feeding.
Life Cycle and Seasonal History
In both species, the males attract the females with a mating dance, and then they deposit protected sperm-containing capsules on moist surfaces. Females pick up the capsules, and then they lay around 50 eggs in dark crevices, food, or dust. Silverfish eggs hatch in two to four weeks, and firebrat eggs hatch in about two weeks. Eggs can remain dormant for approximately six weeks in colder environments. Nymphs are quite small, about 1/16 of an inch, and they are plump with no scales. They acquire their signature scales after their fourth molt, and that is when they begin to resemble adults. Silverfish and firebrats will molt continuously through their life. Silverfish live approximately three years; firebrats live about two years.
Silverfish and firebrats are active during the night, and little activity is observed during the day.
Human Interaction and Urban Impact
Silverfish and firebrats are not cause for a health concern. They are not associated with the spread of disease. They have very weak mandibles, so they are unable to bite.
Silverfish and firebrats are primarily nuisance pests, although in large numbers they can be minor pests. They both can contaminate foods and damage paper products, like wallpaper and book bindings. Serious damage is only found in cases of high silverfish and firebrats populations over a long period of time.
Prevention and Management Approaches
To limit harborages, seal the crevices and cracks around the building’s foundation, walls, baseboards, and cupboards. Another way to prevent an infestation is to regularly check the roof of the building to ensure there is proper ventilation to prevent moisture accumulation; this is especially true for cedar shake roofs. Reduce the amount of clutter and food items that may support a silverfish or firebrat infestation.
In the case of a large silverfish or firebrat infestation, reduce the humidity in and around harborage areas by using a dehumidifier or by fixing potential leaky pipes. Sticky traps may be a good way to pinpoint areas of high activity.
Insecticides labeled for silverfish and firebrats are available in the market; look for products with bifenthrin, lambda-cyhalothrin, or cypermethrin as active ingredients. Dust formulation can be useful in wall voids and behind baseboards. Always use precaution and follow the label carefully before using any insecticide. Insecticides have a certain amount of toxicity to mammals; children and pets are especially at risk.
Other Online Resources
University of California, Davis
For information regarding labels of chemical control options, please visit NPIC MAPL
