Storage Pest

Storage PestCommon Stored Pest SpeciesStorage Pest ManagementSilverfish & FirebratsSilverfish & Firebrats Management

Storage Pest

  • Stored products include all durable agricultural commodities that can be dried and stored in bulk, such as cereal grains, flour, oil seeds, legumes, nuts, dried fruits, animal products, and packaged, baked or processed foods
  • Insects have infested stored food products since the beginning of human civilization
Weevils (Family Curculionidae)
  • The adult weevil can be readily identified by its long slender snout
  • Adults are less than 3/16 of an inch in length, and color varies from medium brown to black
  • The thorax is pitted with elongate depressions, and there are no wings under the wing covers, so the species is flightless
  • The granary weevil female chews a small hole in a kernel, into which she deposits an egg
  • Each female can deposit between fifty and two hundred and fifty eggs

Lesser Grain Borer (Rhizopertha dominica)
  • The adults of this species are readily distinguished by the squared-off appearance at the front of the body
  • The adults are less than 1/8 of an inch in length and range from reddish brown to dark brown
  • This species is a good flier, and adults are readily trapped in pheromone-baited traps at harvest
  • The lesser grain borer is a long-lived species and a female can lay up to 500 eggs
  • Heavy infestation with lesser grain borers can be identified by a sweetish, musty odor in the storage. This odor is a result of the male-produced aggregation pheromone that has been demonstrated to be an effective lure for use in traps

Flour Beetle (Tribolium castaneum)
  • These elongate, shiny beetles have short, clubbed antennae
  • Flour beetle is seldom found in grain and is more often associated with milled products
  • The insects reproduce faster when some fine material is present in the stored grain especially if grain moisture is more than 12%
  • Under optimal conditions females can lay up to 450 eggs over a lifespan that may be as long as eighteen months
  • The adults are good fliers
  • A pungent, bad odour in the grain is a sign of a large infestation of flour beetles

Drugstore Beetle (Stegobium paniceum)
  • The adults are about 1/10 of an inch in length, cylindrical and uniform brown with fine silky hairs
  • The adult drugstore beetle has a three-segmented, sawlike antennae that is pressed to the body when at rest
  • This beetle lays eggs in almost any dry organic substance
  • The entire life cycle may be passed in less than two months

Tobacco Beetle( Lasioderma serricorne)
  • The tobacco beetle is a small stout, oval, reddish-yellow or brownish-red beetle, with the head bent down nearly at a right angle to the body
  • It varies in size, but is usually about 1/10 of an inch long
  • The antennae of the tobacco beetle are saw-like and the head is somewhat retracted
  • The adult tobacco beetle lives 2 to 4 weeks, during which time each female may lay as many as 100 eggs

Rusty Grain Beetle (Cryptolestes spp.)
  • These small insects (2 mm) are readily identified by their very long antennae
  • The antennae of both male and female rusty grain beetles are about half the length of the body
  • The rusty grain beetles have been recorded from wheat, flour, oilseeds, cassava root, dried fruits, and chilies
  • The adults are good fliers
  • Females can lay up to 400 eggs over a lifespan of up to nine months

Saw-Toothed Grain Beetle (Oryzaephilus surinamensis)
  • Saw-toothed grain beetle is a slender, flat, brown beetle about 1/10 of an inch long
  • It gains its name from the peculiar structure of the thorax, which bears six sawtooth-like projections on each side
  • The female beetle lays 43 to 285 eggs
  • Eggs are deposited on cracks in the kernels and adults and larvae feed on damaged kernels, fines, and occasionally the germ of the intact grain
  • This species is a good flier, but is most commonly associated with areas of high temperature and humidity

Khapra Beetle (Trogoderma granarium)
  • The adults are oblong-oval beetles, approximately 1.6 to 3.0 mm long by 0.9 to 1.7 mm wide
  • Males are brown to black with indistinct reddish brown markings on elytra. Females are slightly larger than males and lighter in color
  • The head is small and deflexed with a short 11-segmented antennae
  • The antennae have a club of three to five segments
  • The adults are covered with hairs
  • Adult khapra beetles have wings, but apparently do not fly and feed very little
  • This beetle has never been observed to fly; therefore, its spread is probably dependent on movement of infested goods or in containers where it may be transported while in diapause

Angoumois Moth (Sitotroga cerealella)
  • Angoumois grain moth adults are brownish gray, slightly less than 1/2 inch long, with a long fringe of hairs on the wings
  • The forewings are clay-yellow and without markings; the hindwings are gray
  • Angoumois grain moths can be found infesting a variety of grain and food materials. They attack all cereal grains, however are most often found in corn and wheat
  • It is the only storage pest that will attack standing grains in the field

Indianmeal Moth (Plodia interpunctella)
  • Adult moths are about 3/8-inch (8 to 10mm) long when at rest and have a wing spread of about 1/2 to 3/4 inch (18 to 20mm)
  • The overall body color is generally dirty gray but the tip half of the wing is rusty brown or nearly bronze
  • This wing marking pattern allows Indian meal moth to be easily distinguished from other household moths
  • Indian meal moths develop in many kinds of stored foods. Coarsely ground grains and cereal products are commonly infested
Empty-Bin Treatment

Empty-Bin Treatment

  • Empty-bin insecticide applications are encouraged to prevent the infestation of new grain by existing insect populations
  • After bins have been properly cleaned and inspected and prior to adding new grain, spray to run-off the inside surface and as much of the outside, including the nearby ground surfaces, aeration ducts, and grain handling equipment, as possible
  • Sprays should be concentrated on cracks, crevices, and areas difficult to clean
  • Applications should be made at least two weeks prior to adding new grain
  • Allow 24 hours for sprays to dry
  • These treatments provide a barrier to insects that may be attracted to the storage facilities and also provide control of the insects not removed during the cleaning operation

Chemical Grain Protectants
  • Grain protectants are insecticides sprayed directly onto grain going into the storage or already in storage
  • Protectants will not eliminate existing infestations
  • Protectants are recommended if grain is going to be stored for extended periods, in flat structures, under circumstances that favour pest development, or in facilities with a history of insect damage

  • Fumigant insecticides are the best tools for quickly reducing insect pest infestations in food processing structures and bulk grain storages
  • The goal of fumigation is to maintain a toxic concentration of gas long enough to kill the target pest population.
  • The toxic gases penetrate into cracks, crevices, the commodity, and the facility treated.
  • Fumigants provide no residual protection

Fumigants come in several forms and formulations . Methyl bromide and phosphine producing materials such as magnesium phosphide and aluminum phosphide are the most common

  • Phosphine fumigants
    • Phosphine has no adverse effects on seed germination when applied according to label directions and at labeled rates
    • Phosphine does react with certain metals such as copper, brass, bronze, gold, and silver
    • Reactions result in discoloration and corrosion
    • Since the gas diffuses through the grain rapidly, structures must be sealed properly, especially under cooler conditions
  • Methyl bromide fumigants
    • Under most conditions, fumigation with methyl bromide will not harm germination.
    • However, high doses for more than 24 hours coupled with temperatures above 85° F and moisture greater than 12 percent can negatively impact seed germination
    • Methyl bromide does not harm electronic equipment and wiring, and requires less time to kill insects when compared to phosphine, but does give certain products containing sulfur, rubber (foam and sponge rubber also), feathers,hairs, and cinder blocks an odour

Silverfish & Firebrats

  • Silverfish and firebrats are wingless, flat insects with two long, slender antennae on the front and three long, slender bristles at the rear of a tapered, carrot-shaped body
  • Silverfish and firebrats are nocturnal and hide during the day
  • Silverfish and firebrats feed on many types of paper and fabric; particularly attracted to glazed paper or material used in book bindings, which may include starch, glues, or other materials.
  • Often the first indication of a silverfish and firebrats infestation is the evidence it leaves behind. Damaged paper may have notched edges or holes throughout, depending on the severity of the infestation. Book bindings that are attacked by silverfish or firebrats may have ragged edges or markings on the bindings. Silverfish and firebrats may also leave cast skins, scales, and/or feces on attacked materials


  • Adult silverfish are about ½ – ¾” in length with light gray, dark gray or silver-colored scales
  • A silverfish female may lay over 100 eggs during her lifetime. Eggs are laid singly or in small groups, hatching in three to six weeks
  • Silverfish prefer cool, damp areas, and are often found in bathrooms, basements, and in bookshelves or other areas where rarely used items are stored
  • Silverfish are most active at night and run very swiftly with a wiggling motion that resembles the swimming action of a fish


  • Adult firebrats are about ½” in length and can be gray in color, but usually the scales are brown and mottled in appearance
  • Firebrats lay about 50 eggs at one time in several batches. Eggs hatch in about two weeks under ideal conditions
  • Firebrats prefer areas of high temperature (90° F and above) and high humidity. Therefore, firebrats are more common in attics and around furnaces, ovens, and water heaters.
Residual Spraying
  • Residual insecticides usually provide 15-45 days of control and should be applied to the areas where the silverfish and firebrats are most commonly seen
  • Residual spraying into cracks and crevices in doors and window casings, along edges and intersections such as baseboards, in closets, bookcases, and places where pipes go through walls, and into voids and other suitable, dark hiding places where silverfish or firebrats are found

  • If a silverfish is seen and damage is severe, fumigation can be expedient since silverfish sometimes are found lurking outside of the books
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