Silverfish and Firebrats
 Description: Silverfish and firebrats are slender, wingless insects,
one-third to one-half inch long with three, long bristletails at the end of
their body. Silverfish are shiny and silver or pearl gray. Firebrats are mottled
gray or tan. B oth are extremely fast runners and are often seen only when
trapped in wash basins or bath tubs, where they are unable to climb the smooth
vertical surface to escape. They hide during the day and feed at night.
Life cycle: A single silverfish female will lay less than 100 eggs
during her lifetime she deposits them in cracks and crevices or behind
baseboards in damp and warm locations. The eggs are elliptical and 1 mm long;
they take between two week s and two months to hatch depending upon conditions.
Firebrat females lay only about 50 eggs in a lifetime and firebrats require a
humidity of fifty percent or higher. Firebrat eggs fail to hatch below 70 F and
prefer temperatures above 90 F. The silve rfish life span can be three to four
months if the house is warm and humidity high or as long as two to three years
under less favorable conditions.
Foods preferred: Silverfish and firebrats will eat any of the foods
humans eat and also starch, glue, paste, sizing in fabrics, and dead animals
even to the extent of cannibalizing dead or injured members of their own species
or their castoff skins.
Damage: These insects will damage starched cotton, linen, and silk, as
well as bookbinding's, wallpaper, or rayon drapes. The damage often appears as
irregular patches of glaze removed from wallpaper or irregular and notched edges
on wallpaper or other paper products. Scales, excrement, or yellowish stains on
paper or fabric can also indicate the presence of silverfish or firebrats. They
seldom damage fibers of animal origin such as wool or hair. Where found:
Silverfish can be found anywhere in the house in attics, between walls, under
floors, under sinks, in cupboards, and along pipes. They can also be found
between rayon drapes and the lining. Firebrats prefer much warmer areas in the
house, such as warm attics in the summer, furnaces, hot water heaters, stove,
and oven areas, fireplaces and hot water pipes places where it is very warm and
possibly damp.
These insects and their eggs are often brought into the home in cardboard
cartons, books, papers, starched and rayon fabrics, and other carbohydrate
materials.
Prevention and control: Clean up areas where wood, cardboard boxes,
old papers or books are stored, and where these insects are noticed.
Spray areas where silverfish or firebrats are seen-usually around closets,
shelves, under and around sinks, around steam pipes, baseboards, window casings,
and places where pipes go through the walls and, in the case of firebrats, near
heat pipes or s tove or furnace areas. There are many pesticides under many
brands. Select one labeled for use against silverfish or firebrats with
directions for the situation in which they have been found. Dusts are frequently
more desirable than sprays. Be careful not to use oil-based sprays around
electric motors, gas pilot flames, or other places where they might start fires.
If you are troubled with firebrats and not silverfish, you may need to apply
insecticide only to warm parts of the house. A light mist o f residual
insecticide spray can be applied to corners and both sides of infested
draperies.
Results may not be immediate but, if the insecticide is properly and
thoroughly applied, it will leave a residue that should be effective within a
few weeks. If satisfactory control is not achieved in two or three weeks, make
an additional applicatio n.
Trapping: Where application of pesticides is undesirable, silverfish
and firebrats can be trapped by covering the outer surface of a small jar (like
a one-ounce ointment jar) with masking tape and allowing the insect to climb up
the outside. No bait is needed. The insects fall into the jar and can't climb
out of the smooth inside walls. The traps should be placed in paths normally
used by silverfish, such as intersections and corners of kitchen cupboards or
bookcases or next to the baseboard on the floor.
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| Jeffrey Tucker is president of Entomology
Associates, Houston. Questions can be sent to Questions & Answers,
c/o Entomology Associates, P.O. Box 70375, Houston TX 77270, or faxed to
713/681-9069. |
SILVERFISH VS. FIREBRATS
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Q: I am not sure of the difference between
silverfish and firebrats. Is this a case where the same insect has two
different names or are they two different pests? Is control the same or
is there some difference? (L.C.)
A: Both silverfish and firebrats belong to the same insect
order, Thysanura. They are also typically placed in the same family.
Depending on whom you consult, there may be as many as eight to 10
different species of silverfish in North America and only one species of
firebrat. Beyond that there are both similarities and differences in
their appearance and behavior.
At first glance, both silverfish and firebrats appear similar. On
closer inspection, firebrats tend to have longer antennae that often
extend past the tip of the abdomen. Also, firebrats tend to be a mottled
gray color with patches of dark gray and lighter silver over the dorsal
surface of the body. Silverfish tend to be uniformly gray or silver in
color, although there is at least one species with dark lines extending
down the length of its back.
Both silverfish and firebrats are often referred to by another common
name, bristletails. Obviously, this name refers to the long appendages
attached to the tip of the abdomen. If you are interested in definitely
identifying either firebrats or silverfish, you may want to refer to an
excellent key found in the chapter on these two insects in the 8th
edition of the Handbook of Pest Control.
Both silverfish and firebrats tend to prefer warm, moist areas.
However, this may be misleading at times. While an area may appear warm
(such as a furnace or heater room), there may not be an obvious source
of moisture. In my experience, both silverfish and firebrats generally
have a very low moisture requirement and can easily find moisture
sources such as floor drains, condensate pans and wet walls. Both
insects are most commonly indoors, however, I’ve found that in the
South, both can occur in the peridomestic environment. Clutter in
garages and storage sheds are typical locations for these pests. I’ve
also found firebrats living under tree bark in firewood piles outdoors.
Both insects have chewing mouthparts and can damage a wide variety of
materials. They both appear to have an affinity for starches and animal
proteins. Typically we find silverfish feeding on paper and some cloth
materials. It should be noted that both silverfish and firebrats are
extremely resistant to starvation and can exist without feeding for long
periods of time. Additionally, both insects are relatively long-lived.
Life spans may exceed three years.
Generally speaking, the control procedure used for German or
brown-banded cockroaches in homes will also be effective for silverfish
and most firebrat infestations. There is some indication that silverfish
tend to roam more widely in search of food and harborage and that
firebrats tend to be more localized in their distribution. Also,
remember that under some circumstances, firebrats exist in the near
outdoor environment and may be brought into a structure in infested
materials.
If the infestation is severe and of long duration, a number of
non-chemical steps may be taken to reduce the suitability of the
environment for these two insects. Generally, removing or reducing
clutter and other forms of food, as well as reducing the availability of
moisture to include reducing humidity, has been effective in managing
these pests. In most cases, though, to achieve a quick resolution to a
localized silverfish or firebrat infestation you will need to focus on
treating cracks and crevices, as well as void areas in and adjacent to
the environment where the pests were seen. Most residual insecticides
will be effective against these pests. It is important also to remember
that the use of dusts, including inorganic materials, can provide not
only immediate relief but also long-term control. Currently, I don’t
have enough information to determine whether or not any of the baits
used in cockroach control will also be effective on silverfish. Perhaps
that will be looked into in the near future.
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