Foreign grain beetle
Encyclopedia
Ahasverus advena, also referred to as the foreign grain beetle belongs to the beetle
family Silvanidae, as does its relative the sawtoothed grain beetle.
, approximately 2 mm ( in) in length. This beetle can be distinguished chiefly by slight projections or knobs on each front corner of the pronotum, and its club-shaped antennae. The larvae are worm-like, cream-colored and often reach a length of 3 mm before pupating into darker adults. Males and females are identical in appearance both as larvae and adults.
Adults are a reddish brownish color (occasionally black).
They are very similar to the saw-toothed grain beetle
, but lack the "sawtoothed" projections on the pronotum. These small beetles are strong fliers, and are often confused with fruit flies
or gnats
. However, these beetles are hard shelled, and lack clear wings. Some people can mistake them for flea
s or lice, but neither of those insects can fly.
or fungi
. They acquired their name because they are often found feeding on moldy grain. However, grain injury by this pest is not severe enough to cause noticeable economic loss. They can appear near bathtubs, sinks or any moist area. They can enter houses from the walls near pipes.
s, fruit flies
and flea
s.
Diatomeacous earth is a ecological alternative to pyrethrins and can be effective in treating stored goods and their areas against this insect.
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
family Silvanidae, as does its relative the sawtoothed grain beetle.
Identification
The foreign grain beetle is a rather small beetleBeetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
, approximately 2 mm ( in) in length. This beetle can be distinguished chiefly by slight projections or knobs on each front corner of the pronotum, and its club-shaped antennae. The larvae are worm-like, cream-colored and often reach a length of 3 mm before pupating into darker adults. Males and females are identical in appearance both as larvae and adults.
Adults are a reddish brownish color (occasionally black).
They are very similar to the saw-toothed grain beetle
Saw-toothed grain beetle
The sawtoothed grain beetle, Oryzaephilus surinamensis, is a slender, dark brown beetle 2.4–3 mm in size, with characteristic "teeth" running down the side of the prothorax. The sawtoothed grain beetle is a primary pest, in the UK, that attacks damaged grain...
, but lack the "sawtoothed" projections on the pronotum. These small beetles are strong fliers, and are often confused with fruit flies
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
or gnats
Gnats
Gnats may be:*Plural of Gnat*GNATS the GNU bug tracking system*Folland Gnat Aircraft...
. However, these beetles are hard shelled, and lack clear wings. Some people can mistake them for flea
Flea
Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...
s or lice, but neither of those insects can fly.
Distribution
The foreign grain beetle is found in both tropical and temperate regions, since the temperature for complete development lies between 20 to 35 °C.Behavior
They usually become apparent in early summer to late fall when humidity levels are highest. These beetles can only survive if relative humidity exceeds 70%. Unlike their name suggests, the only things they eat are moldMold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
or fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
. They acquired their name because they are often found feeding on moldy grain. However, grain injury by this pest is not severe enough to cause noticeable economic loss. They can appear near bathtubs, sinks or any moist area. They can enter houses from the walls near pipes.
Life cycle
Adult females can begin laying eggs around 3–4 days after pupating to an adult female. Daily oviposition rates are 1-4 eggs, but can be as high as 8–12 eggs. These eggs are laid singly or in clusters of two or three, and hatch in 4–5 days. The larval stage is completed in 11–19 days, and then it will pupate for 3–5 days. Under laboratory conditions, and a temperature of 27°C, the transition from egg to adult beetle takes around 3 weeks. Larval development times increase with decreasing humidity. Mated males and females have an average life span of 159 and 208 days, respectively. Unmated beetles live considerable longer, with a life span of about 275 days for males, and 300 days for females.Impact on humans
These are harmless insects that sometimes inhabit dwellings. They infest a number of products such as grains, cereal products, oilseeds, dried fruit, and spices. An infestation will occur if mold has grown on these products already due to a damp environment. Hence, these beetles are considered good indicators of damp storage conditions, and spoiled food.They do not bite or damage wood, fabric or stored food. They only feed on the mold and fungi that has grown on them. They are especially problematic in new houses due to the mold and fungal growth on new lumber, or wet wall board . In homes, they can be confused with tickTick
Ticks are small arachnids in the order Ixodida, along with mites, constitute the subclass Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians...
s, fruit flies
Drosophilidae
Drosophilidae is a diverse, cosmopolitan family of flies, which includes fruit flies. Another family of flies called Tephritidae also includes fruit flies. The best known species of Drosophilidae is Drosophila melanogaster, within the genus Drosophila, and this species Is used extensively for...
and flea
Flea
Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...
s.
Control
The best way to control them is to vacuum your house at least three times a week, and eliminate the damp source. New homes naturally dry out within the first few years, and drying times can be accelerated by increasing ventilation by means of fans or air conditioning. Aerosol sprays of grain insecticide containing pyrethrins can also be used, but must be applied frequently. However, these Grain-Protectant insecticides will not kill the insects inside the grain kernels.Diatomeacous earth is a ecological alternative to pyrethrins and can be effective in treating stored goods and their areas against this insect.
Biological control
Various insect predators and parasitic wasps can be used to attack this beetle. However, they are only effective when used in large numbers. Biological control is generally not used because in the U.S., the Food and Drug Administration (FDA) and food processors do not permit the use of live insects in raw grain.External links
- Foreign Grain Beetle on University of Minnesota, Yard & Garden Brief
- Foreign Grain Beetle on University of Kentucky College of Agriculture
- Foreign Grain Beetle on PestWeb, Government of Australia
- Foreign Grain Beetle on Canadian Grain Commission
- "Foreign Grain Beetle" on Iowa State University, Department of Etymology