TWOBANDED JAPANESE WEEVIL, Callirhopalus bifasciatus (Roelofs), COLEOPTERA
The twobanded Japanese weevil is about 1/4 inch long. It is light or dark brown with a short, blunt snout. The wing covers (elytra) are striped with indistinct white lines in the grooves, white spots on the apical half, and a dark brown or black transverse band. The eggs are small and cream colored. They are laid in small masses and sealed inside a folded leaf. The larvae are typical weevil grubs: white, legless and with a brown head. They are about 5/16 inch long. The pupa is white with brownish hairs. They are about 1/4 inch long.
The twobanded Japanese weevil is parthenogenetic (no males have been found). Eggs are deposited in folds along the margins of leaf fragments or in dead leaves that have the free edge sealed to form a pod. After hatching, the larvae burrow into the ground and feed on roots. These weevils have fused wing covers and no flight wings and thus are unable to fly. They feed during the day, but if disturbed, drop to the ground readily and remain motionless. There is only one generation each year.
Twobanded Japanese weevils are apparently resistant to carbaryl (Sevin), diazinon,
and malathion. Two small demonstrations conducted in 1981 indicated that acephate
(Orthene) at the labeled rate gave good control when applied as a foliar spray
and drench. Azatin EC is specifically labeled with a full Federal registration
for the twobanded Japanese weevil although this pest is not listed on the label.
In addition, some labels of the following pesticides are worded to allow their
use for twobanded Japanese weevil under Section 2 (ee) of the Federal Insecticide,
Fungicide and Rodenticide Act.
Commercial growers and landscapers can use a pyrethroid (Astro, Mavrik, Talstar
or Tempo 2) for control. Homeowners may find BioNeem and formulations of cyfluthrin
or permethrin at lawn and garden centers.
Tests on the similar black vine weevil show pesticides may be applied to the media or soil surface as a drench to control black vine weevil larvae. Imidacloprid (Merit, Marathon) can be used as a soil injection or drench against larvae. Scimitar & Demand (Oregon study) and Talstar (Ohio study) are effective when adults are present. Aloft may also be an effective product.
| Pesticide (Trade Name) | Formulation | Amount |
| acephate (Orthene) | 75% soluble powder | 1 tablespoon per gallon for Tree and Ornamental) 1 pound per 100 gallons of water. (Not labeled for the twobanded Japanese weevil but labeled for black vine weevil, strawberry root weevil, root weevil, and numerous other pests on many ornamental plants.) |
| acephate (Orthene) | 9.4% emulsifiable concentrate | 3 tablespoons per gallon of water. (Not labeled for the twobanded Japanese weevil but labeled for black vine weevil, obscure root weevil, and numerous other pests on many ornamental plants.) |
| azadirachtin (Azatin EC, BioNeem) | 3% emulsifiable concentrate | Azatin EC is federally labeled for twobanded Japanese weevil but the pests and rates of application are not listed. |
ENT/ort-34 August 1994 (Revised), Scientific name corrected on 08 Oct 96
Web page last reviewed January, 2011 by the webperson.
