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 SPIDER BEETLES
Common Name Scientific Name
Hairy Spider Beetle Ptinus villiger (Reitter)
Whitemarked Spider Beetle Ptinus fur (Linnaeus)
Brown Spider Beetle Ptinus clavipes Panzer
American Spider Beetle Mezium americanum (Laporte)
Australian Spider Beetle Ptinus ocellus Brown
 Spider beetles are general scavengers. They feed on a variety of items, such as
cereals, seeds, flour, meat, dried fruits and vegetables, fish food, dead
insects, rodent droppings, old wood, cayenne pepper, roots, cocoa, sugar, drugs,
and spices. Common sites of infestation in the house include wall voids and drop
ceilings. Spider beetles are primarily warehouse pests, attacking various seeds
and certain whole grains, such as wheat, barley, rye, and flax. Also, serious
infestations have been found in flour and feeds, such as bran shorts and meal
preparations. Larvae cause a typical "scarring" of the wood in buildings in the
formation of pupal cells prior to pupation. Spider beetles sometimes become
prominent cereal pests in Canada and the northern United States. Some have been
found quite active even during freezing weather. They do not bite or sting
humans or pets, spread diseases, or feed on or damage the house or furniture.
Identification
Adult spider beetles are minute oval or cylindrical insects with long legs
resembling giant mites or small spiders. The head is often hidden when viewed
from above. They are 1/16- to 3/16-inch long with long filamentous antennae
(usually 11 segmented) arising on the front of the head close together at the
base. Most are brownish-black with a large, globe-like abdomen and the prothorax
(first segment behind the head) constricted at the base of the wing covers.
Larvae are C-shaped or grub-like and cream-colored with short legs. The
segmented abdomen contains many long hairs.
The hairy spider beetle is reddish-brown with two irregular- shaped white
patches on each wing cover. The whitemarked spider beetle has a reddish-brown
body covered with yellow hairs; the females have two white patches on each wing
cover that join to form two transverse bands. The brown spider beetle is
uniformly dark brown without scales on the wing covers. The American spider
beetle is dark, reddish-brown to nearly black with a shining subglobular body.
The Australian spider beetle is dark reddish-brown and the wing covers are
covered with golden brown or yellowish hairs.
 Life Cycle and Habits
Adult hairy spider beetles usually appear during the spring. The female lays up
to 40 eggs. Eggs are spindle-shaped, pearly, and about 1/32-inch long. Eggs may
be laid on the outside of the grain sacks or in flour debris in cracks and
corners. Eggs hatch into larvae that reach a body length of almost 1/8 inch.
Cream-colored larvae with brown heads develop in three months and molt three
times with a pupal cell in the flour debris. Larvae often bore into wood or
cardboard boxes to overwinter in the pupal cell with actual pupation occurring
the following spring. Some spider beetles can remain active during the cold
months, especially in older buildings where sources of food have accumulated.
Spider beetles may become pests in homes, warehouses, grain mills, museums, etc.
They are attracted to moisture, excrement, and abandoned animal nests.
Control Measures
Spider beetles are primarily pests of cereal products, which often remain in
storage for long periods. Serious infestations have been found in flour, bran
feeds, and meal preparations. Sometimes, infestations are detected by the
typical "scarring" of the wood in buildings by the larvae during the formation
of pupal cells before pupation occurs.
Prevention
Practice strict sanitation measures. Thoroughly clean storage facilities
beforehand by use of a strong suction vacuum cleaner to eliminate favorable
development places. Inspect stored foods routinely and eliminate any dampness or
high humidity conditions. Eliminate rodents, birds, and other insects as spider
beetles feed on feces and dead insects.
Non-Chemical Extermination
The simplest and most effective control measure is to locate the source of
infestation and quickly exterminate it. Use a flashlight or other light source
to examine all food storage areas and food products. Dispose of heavily infested
foods in wrapped, heavy-plastic bags or in sealed containers for garbage
disposal service or bury deep in the soil if practical and regulations allow. If
detected early, the problem may be solved.
At the time of purchase, carefully examine foods such as pancake flour, flour,
cornmeal, raisins, dry dog and cat food, old tobacco, ginger, dates, red pepper,
rice, and macaroni. Check the packaging date to establish freshness. Examine
broken and damaged packages and boxes to avoid bringing these stored product
pests accidentally into the home. Purchase seldom-used foods in small quantities
to prevent long storage periods of one month or more, especially during the warm
summer months. Store susceptible foods in insect-proof containers of glass,
heavy-plastic or metal, ideally with screw-type lids, or store in a freezer.
Use older packages first before new ones, avoid spillage in cabinets, and always
keep food-storage spaces clean. Properly ventilate the storage area to discourage
these moisture-loving pests.
Lightly infested or suspect foods with questionable infestations can be heated
in a shallow pan in the oven at 120 degrees F for one hour or at 130 degrees F
for 30 minutes, or placed in a deep freeze at 0 degrees F for four hours. Some
kill infestations by placing the product in a microwave oven for five minutes.
Heat-treat dried fruits or vegetables by placing them in a cheesecloth bag and
dipping in boiling water for 6 to 10 seconds. Seeds saved for planting may have
the germination reduced by super-heating or cooling. Sifting the food material
will remove possible insect fragments, and any remaining will not cause harm if
consumed. After insects are killed, contaminated food might be used outdoors
during the winter months for bird feed.
Careful sanitation is the best method to avoid stored product pests. After
removing all food, food packages, utensils, and dishes from the cupboard,
shelves, or storage area, use a strong suction vacuum cleaner with proper
attachments to clean all spilled foods (cornmeal, toaster crumbs, bits of pet
food, raisins, etc.) from the cracks and crevices, and from behind and under
appliances and furniture. Pull heavy appliances from the wall and scrub with
soap and hot water. The ability of these insects to find a small amount of food
is amazing. After shelves are thoroughly dry, cover with clean, fresh paper or
foil before replacing with food or cooking utensils. Pheromone traps/lures are
commonly available from: Insects Limited, Inc., 10540 Jessup Blvd.,
Indianapolis, IN 46280. The phone number is: 1-800-992-1991.
Insecticides
Household insecticides have no effect on insects within food packages.
Pyrethroids will kill spider beetles. However, repeat treatments will be needed to
control newly emerging adults. Residual labeled contact insecticides applied directly
to cracks and crevices in the storage areas will help control. Dust formulations
applied to wall voids and other hard-to-reach places can be effective. Before using
any insecticide, always read the label, following directions and safety precautions.
_____________________________________________________________________
All educational programs conducted by Ohio State University Extension are
available to clientele on a nondiscriminatory basis without regard to race,
color, creed, religion, sexual orientation, national origin, gender, age,
disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU
Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868
Locations
Serving the St. Louis Metropolitan area since 1956, including
Arnold, Ballwin, Chesterfield, Crestwood, Creve Coeur, Des Peres,
Fenton, Florissant, Kirkwood, Maryland Heights, Overland, St.
Charles, Webster Groves, Wentzville and surrounding areas.
In Illinois: Belleville, Collinsville, Edwardsville, Columbia,
Madison, Waterloo, O’Fallon, Granite City, Alton, St. Clair, Monroe
and surrounding areas.
Columbia & Jefferson City, MO and surrounding areas.
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