[Pest Profile] Silverfish

Description

Silverfish are primitive, wingless insects that are 1/2-inch long when fully grown. They are covered with silvery scales and are flattened and somewhat "carrot" shaped. Three long, slender "antennae-like" appendages project from the end of the abdomen, giving them the name "bristle tails."

Biology

The female lays one to three eggs per day in crevices or under objects. Eggs hatch in about 43 days. Young silverfish look exactly like adults, except smaller, and feed on the same foods. Under ideal conditions, they molt every two to three weeks becoming adults in three to four months. However, under poor conditions, this might require two to three years. These insects are very long-lived, commonly living at least three years. Silverfish are unlike most other insects in that they continue to molt after they become adults.

Habits

Silverfish are tropical insects that easily adapt to the structural environment. They live in warm (71-90°F), moist locations in structures; hide during the day; and rest in tight cracks and crevices. They roam great distances looking for food, but once a food source is located, they remain close until the supply is exhausted. They can be found throughout a structure from the basement to individual floors to attics to shingles on the roof. Outdoors, they can be found in mulch, and under siding and roof shingles, particularly cedar shakes. They seem to be especially fond of the sizing on books and paper, and the glues and pastes found on wallpaper, labels and paper products.

Control

During the inspection, look for activity in areas that provide moisture, harborage and food. Reducing moisture, lowering the temperature, and removing infested items can help eliminate localized infestations. Sanitation is helpful but may not greatly reduce the problem because these pests feed on so many paper products. They can survive for weeks without food and water. Silverfish are easily controlled with careful and thorough applications of baits and/or residual insecticide sprays and dusts. Care should be taken to treat wall voids, cracks and crevices, and other suspected harborage areas thoroughly. The same careful application of residual insecticides used for good cockroach control is needed to effectively control silverfish. Outdoors, microencapsulated or wettable powder formulations should be used.