Weevils in the Garden

Weevils In the Garden

Annotated Checklist of the Weevils of North America, Central America, and the West Indies

Strawberry Root-Weevil [Image]

Many species of root weevils feed on the young roots and crowns of strawberry plants. Adults will eat notches in the leaves, this damage is minimal, and unless you have a sever infestation will not generally damage your crop..
The larvae/Grubs However cause severe damage by tunneling in roots and crowns of plants. Damaged plants are stunted and darkened with leaves closely bunched. Plants may be weakened or even killed. Often the damage is restricted to a circular area in field due to the tendency of adults to gather in large groups.
In their adult stage this insect is a small, dark snout beetle with rows of pits along their backs. Various species will differ slightly in size and color. The strawberry root weevil is black to light brown and 1/5 inch, the rough strawberry weevil chocolate brown and 1/4 inch, and the black vine weevil is black with small flecks of yellow on its back and 2/5 inch.
The grubs are white, 1/4 to 1/2 inch long, and a characteristic "c" shape. These grubs can be distinguished from other soil grubs because they are smaller and legless with a lighter colored head.

Root weevils overwinter in the soil as grubs that pupate in the spring. Adult beetles emerge in late May through June, feed at night on foliage leaving characteristic leaf notching, and hide during the day. After feeding for as short as 10 to 14 days to as long as 30 to 60 days they begin laying eggs in soil near strawberry plants. The eggs hatch in late summer or early fall and the grubs start feeding on the roots. Most damage is caused by grubs after resuming feeding in the spring.

To prevent spread of root weevils to new beds, plow under old beds as soon as possible. Post harvest foliar sprays to control adult weevils prior to egg laying is recommended at renovation. Growers should watch for leaf notching as an indication of adult emergence.

Rough Strawberry Root Weevil
Adults are slightly more than 1/4 inch long and resemble the strawberry root weevil with the exception of size. They are black, shiny, without scales and with coarse, punctures on the outer wings.

Adults are common on fruit trees in early summer. Adults feed at night and hide during the day. Common victim of Praying Mantids

Carrot Weevil      [Image]
The carrot Weevil adult is a dark-brown snout beetle about 6 mm long It over winters in plant debris in and about carrot fields that were infested the previous year.>> (Another good reason for Crop Rotation )

In spring, adults become active and mate after a few warm days. They are capable of laying eggs by mid- to late May. However, they do not attack the new crop of carrots until the first true leaf stage. Adult females chew small cavities in the petioles or crown of the carrots , sealing the cavity with a black exudate. Eggs hatch after one to two weeks and the young larvae tunnel down into the root or leave the stalk and enter the roots from the soil. Some young plants may wilt and die.
Black Vine Weevil   [Image]
The adult is a about 3/8 inches long, black and wingless . All of the weevils are females and they reproduce parthenogenetically . Since they do not fly, they migrate primarily by walking The weevils feed at night, making the prying Mantid a good choice of predator. They feed on foliage, chewing out notches, damage is usually not severe.

The grub is a legless, white larva with a wrinkled c-shaped appearance. It is found in the soil under host plants.

Larval feeding occurs through the growing season . They burrow deeper in the ground to overwinter and resume feeding the following spring.

Organic Controls

Nematodes
Beneficial Nematodes, 7 million active units
As Weevils move through the soil they are extremely vulnerable to Nematodes which are microscopic non-segmented worms which occur naturally in soil Thousands of strains exist. Beneficial nematodes only attack soil dwelling insects and not plants . The nematodes enter the host through body openings or by penetration of the body wall. Once inside they release a bacterium which kills the host within 48 hours.

Diatomaceous Earth is highly effective against the soft bodied Grubs.

Organic Pest Control: Diatomaceous Earth Mastergardening Brand 3.6 lbs

Chemical Controls
Malathion Spray: 50 Percent Concentrate 8 oz.

Note; Insecticide labels provide an extensive amount of information and indicate that the insecticide has been extensively tested, and evaluated by the EPA . Insecticides cannot be legally registered, much less sold, without going through these procedures. Among the information included on an insecticide label is the "directions for use", and perhaps more importantly, information with regard to the toxicity of the chemical. Any chemical is potentially toxic .
READ THE LABEL BEFORE APPLYING ANY PESTICIDE. & Follow all label directions. This publication contains pesticide recommendations. Changes in pesticide regulations occur constantly, some materials mentioned may no longer be available, and some uses may no longer be legal.