Page 58 - AG 7-2011 Revised 2016

Obscure Root Rice Weevil Granary Weevil
Weevil
2 MM Grid

Photo Courtesy of UNIVAR Photo Courtesy of UNIVAR

Black Vine Weevil

Photo Courtesy of UNIVAR

1.Antenna- elbowed, clubbed 6.Thorax- yes Grain Weevil

2.Eyes- compound 7.Petiole- none

3.Head- elongated w/chewing mouth parts 8.Abdomen- elytra above abdomen 16

4.Legs- 6 9.Color-brown to black 5

5.Wings- yes 10.Other-also known as snout

beetles & Bill bugs

Life Cycle (GRANARY WEEVIL) Drawing by Andrew Schaible
Eggs are laid in a hole in the grain, which is then plugged up. Females can
lay 30-250 eggs at a time. They hatch into larvae in about 3 days, and then
go through four instars over the next 19-34 days. A pupal cell is formed in the
grain, and after 5-16 days it emerges as an adult. Adults live for 7-8 months,
and the life cycle is completed in 30-150 days, so there are several generations
each year.

Weevils are part of the family of beetles. They are usually noticed as different in that many have an elongated snout,
and are then known as snout beetles. The mouth is at the end of this snout, and they can chew through tough seeds,
nuts, buds, and fruit. There are over 35,000 types of weevils in the world. They normally range in size from 1/4th
inch up to an inch. Most are colored black, some with stripes and/or spotting. Weevils are most active at night.

Root Weevils are small and reddish-brown. They spend most of their lives underground, and as the name suggests,
the larvae attack roots but adults will also feed on foliage. Fuller’s Rose Weevil has become a major pest for the
citrus industry, attacking new growth on trees. The larvae will also attack roots. They are most active from July
through November. Vegetable Weevil larvae and adults attack the foliage of crops and garden plants. The larvae
will also damage the roots, and will go after dichondra lawns. Adults are active in the summer, but the grubs are
most noticed in the spring. Rice Weevils are a problem in warm areas, and are a major pest worldwide. They infest
grains, nuts and seeds, beans, and even grapes. Granary Weevils prefer cooler areas, and get into just about any
grain product. The Black Vine Weevil is almost identical to the Root Weevil, except that it is larger in size.

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