Strawberry Root Weevil
Otiorhynchus ovatus
Biology
Adult strawberry root weevils are brown-to-black,
blunt-snouted weevils that are about 1/3-inch long. The wing covers are
marked by many rows of small pits. Like the strawberry crown borer, the
adult strawberry root weevil cannot fly. Larvae are thick-bodied,
white, comma-shaped, legless grubs that reach approximately 1/4-inch in
length.
The strawberry root weevil overwinters as a full-grown larva, pupa, or adult in soil, or as an adult in plant debris or other protective habitat. Larvae and pupae complete development in the spring, emerging as adults in May or June; overwintered adults become active in strawberries in May.
Strawberry root weevil.
Adult is about 1/3 inch (8 mm) long;
larva is about 1/4 inch (6 mm) long.
Damage
Root weevil adults lay eggs in strawberries
throughout the summer, with each female depositing 150 to 200 eggs in
the soil. Eggs hatch in about 10 days, and larvae burrow through the
soil to feed on roots until they mature or until cold temperatures cause
a suspension of their activity. Damage to roots and crowns caused by
root weevil larvae can weaken, stunt, or kill strawberry plants.
Although adults eat notches from the edges of leaves, their feeding
causes no economic loss.
Control
The cultural practices described for the control
of strawberry crown moth also limit damage from strawberry root weevils,
as flightless adults do not easily reach new plantings if they are
isolated from existing fields and wooded overwintering sites. Where
existing plantings are infested, carbofuran (Furadan 4F) has been
registered in Illinois under a 24© label for root weevil control.
Consult the most recent edition of the Illinois Commercial Small Fruit
and Grape Spray Guide for more information on insecticides.