L-1833
Silverfish and firebrats are common house-invading pests. Considered mostly a nuisance, they also contaminate food with their droppings and scales from their bodies damage paper goods and even stain cloth.
Silverfish and firebrats are usually introduced in the home from some outside source. Considerable time is required for populations to become established, grow and reproduce. Once they are controlled, they generally do not reinfest from outdoors.
Silverfish and firebrats are flattened from top to bottom, elongated and oval in shape. They
are easy to recognize by their lack of wings, three caudal or tail projections and two long antennae.
Their bodies are covered with fine scales which are silvery to brown in color.
Silverfish develop from egg to young to adult and continue to molt throughout their adult life. They are long-lived, surviving from two to eight years.
The silverfish, Lepisma sacchrina (L.), is probably the most important species. The female lays eggs continuously after she reaches adulthood and may lay over 100 eggs during her lifespan. The eggs are deposited singly or in small groups in cracks and crevices and hatch in 3 to 6 weeks. The young are approximately 1/20 of an inch in length. They are white but take on the adult's silver coloring within 4 to 6 weeks. Adults reach a length of about 3/4 of an inch. Silverfish are extremely sensitive to moisture and require a high relative humidity (75 to 95 percent). They also have a temperature preference between 70 degrees and 80 degrees F.
The firebrat, Thermobia domestica, is quite similar to the silverfish, but is considerably
darker. Unlike the silverfish, the firebrat prefers temperatures over 90 degrees F. It also enjoys high
relative humidity, somewhere around 70 to 80 percent. Because of their high temperature
preference, firebrats are commonly found near heating pipes, fireplaces, ovens and other heat
sources.
Silverfish and firebrats are fast running and are most active at night. They generally prefer the lower levels in homes, but are often found in attics as well. They can go for long periods of time, sometimes over a year, without food. They prefer carbohydrates and protein food such as flour, dried meat, rolled oats, paper and even glue. Because they are such general feeders and can survive so long without food, sanitation is of little help in eliminating an infestation. Silverfish are primarily an indoor problem since they are rarely encountered outdoors. They usually are brought into thc home in foodstuffs or other items such as furniture, old books and papers.
Sanitation only helps prevent a reinfestation after a population has been eliminated. It alone cannot control silverfish or firebrats and is only marginally effective in reducing their numbers.
However, a reduction in available water or relative humidity is helpful in eliminating silverfish and firebrats. Dry out or ventilate resting or shelter areas to reduce their moisture level. Since these insects prefer darkness, lighting a sheltered are a sometimes forces them to migrate to sites where they cannot survive or where they can be controlled more readily.
Apply insecticide sprays to sheltered areas, cracks, crevices, around floor moldings, in and behind furniture and in attics. Occasionally, large populations become established in wall voids. It may be necessary to drill small holes in the walls in orde r to treat inside them.
Spraying outdoors is not particularly beneficial, but may help to reduce an occasional reinfestation.
Use insecticide products containing propoxur (Baygon®), bendiocarb, boric acid, dichlorvos (DDVP®), diazinon, chlorpyrifos (Dursban®), malathion, pyrethrins or resmethrin. Dust and aerosol formulations of some of these products are useful in treating attics, wall voids and other hard-to-reach areas that are not subject to wetting or high humidity.
See Extension publication B-1373 House and Landscape Pests for more information on pest control and pesticide products.
It is advisable to use the services of a pest control operator when the infestations are large, persistent and hard to find. A commercial operator has the knowledge, training and equipment to perform safe and effective control.
Insecticide label clearances are subject to change and changes may have occurred since this publication was printed. The pesticide USER is responsible for the effects of pesticide residues on plants or household goods, as well as problems that could ar
ise from contamination of neighboring properties or plants. Always read and follow carefully the instructions on the container label.
The information given herein is for educational purposes
only. Reference to commercial products or trade names is made
with the understanding that no discrimination is intended and
no endorsement by the Cooperative Extension Service is implied.
Educational programs conducted by the Texas Agricultural
Extension Service are open to all people without regard to race,
color, sex, disability, religion, age or national origin.
Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Zerle L. Carpenter, Director, Texas Agricultural Extension Service, The Texas A&M University System.
20M--8-85, Revision
Return
to top of page
Return
to Departmental Home Page
Last modified: January 22, 1997 by Edgar Cross