INTRODUCTION
The red flour beetle gets its common name from its coloration and its
habit of infesting flour. It is one of the most important pests of stored
products found in the home and in grocery stores. It is of Indo-Australian
origin and now occurs worldwide in the warmer climates. In the United
States, it is found primarily in the southern states.
RECOGNITION
Adults about 1/8” (3-4 mm) long. Color reddish brown. Antennae with
abrupt, 3-segmented club. Sides of thorax rounded. Wings functional but
commonly flies only short distances. Except for antennal and thorax differences,
almost identical to confused flour beetle.
SIMILAR GROUPS
(1) Confused flour beetle (Tribolium confusum) have antennae gradually
clubbed, club 4-segmented.
(2) Broadhorned
(Gnathocerus cornutus) and slenderhorned (G. maxillosus) flour beetles
lack antennal club, male mandibles armed with a pair of incurved horns,
length about 1/8” (4.2 mm and 3.2 mm respectively).
(3) Black (Tribolium audax) and false black (T. destructor) flour beetles
black, length about ¼” (5-6 mm and 6-7 mm respectively).
(4) Longheaded flour beetle (Latheticus oryzae) pale yellow brown, antennae
loosely clubbed with last segment smaller and/or narrower than preceding
segment.
(5) Lesser mealworm (Alphitobius diaperinus) with eye almost completely
divided, length about ¼” (5-6 mm).
(6) Yellow (Tenebrio molitor) and dark (T. obscurus) mealworms black,
length about ½-3/4” (12-20 mm).
BIOLOGY
The red flour beetle female deposits about 300-500 clear-white sticky
eggs on or among food materials in cracks, in bags, or through the mesh
of sacks containing food. The female lays 2-3 eggs per day, but lives
for 2-3 years. The eggs hatch in 5-12 maturity in about 30 days under
optimal conditions. The life cycle (egg to egg) can be completed in only
7 weeks, or it may require 3 months or longer. In heated storage facilities
and processing plants, there are 4 or 5 generations annually.
HABITS
These beetles are unable to feed on whole kernels or undamaged grain.
They have been recorded attacking grains and grain products, peas, beans,
shelled nuts, dried fruits, spices, milk chocolate, drugs, snuff, cayenne
pepper, and herbarium, insect, and other museum specimens. They are attracted
to flour of high moisture content.
Adults can fly and
are attracted to light.
Although humans are
not injured by it, red flour beetles do impart a disagreeable odor and
taste to the flour they infest.
CONTROL
Follow the standard control procedures for stored product pests.
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