Secondary pest: Grain feeder and scavengers
- Adults superficially resemble small spiders upon first glance.
- Adults vary in color and may be hairy or devoid of hair.
- Adults range in size from 2 to 4.5 mm long.
- Head is completely or mostly hidden when viewed from above.
- Antennae are very long and similar in length to the legs, giving a spider-like appearance.
- Larvae are white and grub-like in appearance with a well-developed head and thoracic legs.
- Preferred commodity may depend on species
- Cornmeal, bran seeds, grain, spices, grain dust, fishmeal, warehouse sweepings, flour, ground oats, ground barley, wheat meal, rolled oats, stored grain near the surface
- Readily feeds on sound wheat and rye
Signs of infestation
- Contamination with silk, accumulation of granular materials, presence of adults and silken cocoons
- Do not create distinctive damage
- Webbing associated with milled products often reduces grain quality to that of feed
- Larvae may feed in a cluster and web together kernels
- Presence of spider beetles is an indication of poor sanitation
- Approximately 20 species are found in Canada, with more in British Columbia than any other province.
- Certain species are more prevalent in certain locations.
- Most are generalist scavengers feeding on wide variety of materials of plant and animal origin but some species are more specific in their food preferences.
- Pseudeurostus hilleri is widespread and may be found in granaries and warehouses.
- Ptinus fur is widespread.
- Ptinus ocellus is most important in British Columbia and may be found in terminal grain elevators, mills, warehouses.
- Ptinus raptor is most abundant in warehouses in New Brunswick and Nova Scotia and is the most common spider beetle in Ontario.
- Ptinus villiger is found coast to coast in dwellings, granaries and other locations and causes the greatest losses of stored products.
- Life history varies by species, but spider beetles generally prefer higher humidity areas.
- Many species are adapted to lower temperatures (reproduce as low as 10°C).
- Development time varies with time and species.
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