2. Kingdom : Animalia
Phylum : Arthropoda
Class : Insecta
Order : Coleoptera
Family : Curculionidae
Genus : Sitophilus
Species : Oryzae
CLASSIFICATION
3. • Adults are about 1/8 inch long, reddish brown to black
with four reddish or yellowish spots on the wing covers
(elytra).
• The head bears a slender snout and
shield behind the head (pronotum)
has course round punctures.
• The elytra have deep lines
(striae) and course punctures.
• Larvae are legless, white and rotund with a distinct
head capsule.
• The granary weevil has elongated punctures on the
pronotum and is wingless.
Identification Marks
4. LIFE CYCLE OF RICE WEEVIL
ADULT
LARVA INSTARS
EGGS
ADULT
5. Life Cycle
• The female lives 4 to 5 months, and lays a total of
300 to 400 eggs.
• Like the granary weevil, she bores a small hole in
the kernel with her mandibles, lays an egg in it,
and covers the hole with a gelatinous fluid.
• The small, white, legless larva, with a brownish-
black head, has 3-4 instars. In warm weather, the
combined stages from egg to pupa may take as
few as 26 days.
• After emergence, the adult stays in the kernel for 3
or 4 days, hardening and maturing, then bores its
way out.
6. • This weevil is basically a grain pest, but has been
reared from solidified farinaceous products stitch
as macaroni or caked flour.
• The most favorable temperatures for development
are 27 to 30° C.
• Approximately below 7° C, the beetle is dormant.
• It usually dies after 2 weeks of freezing
temperatures, or after an hour at 49° C.
7. • The adults bore into the grain and lay their eggs in
the grain.
• The larva feeds inside a kernel of grain in which
both larva and pupa completes their development.
• Both larvae and adults eat similar food.
NATURE OF DAMAGE
8. • The adult can crawl or fly about and feed
on various products.
• They have been reported to occur on
beans, nuts, cereals wheat products,
and grapes and damage them.
• They have also been observed sucking
the juice from apples and pears,
gradually forming cavities in which they
concealed themselves.
9. Control Measures
• Control of these insects involves inspection
and removal of infested food products.
• Discarding the heavily infested material, repackaging
material in new containers, and vacuuming kitchen
cabinets.
• Rice weevils in all stages of development can be
killed by freezing infected food below 0o F for a period
of three or more days.
• These Rice weevils can also be removed by
heating to 140o F for a period of 15 minutes.
…
10. Control Measures
• Control of these insects involves inspection
and removal of infested food products.
• Discarding the heavily infested material, repackaging
material in new containers, and vacuuming kitchen
cabinets.
• Rice weevils in all stages of development can be
killed by freezing infected food below 0o F for a period
of three or more days.
• These Rice weevils can also be removed by
heating to 140o F for a period of 15 minutes.
…
