How to Manage Pests

UC Pest Management Guidelines

Dry Beans

Wireworms

Scientific names:
Limonius spp. and others

(Reviewed 6/18, updated 6/18)

In this Guideline:


DESCRIPTION OF THE PESTS

Wireworms are yellowish brown soil-dwelling larvae resembling wirelike worms with shiny, tough skin. They are found at all times of the year and in almost any kind of soil. Adults of the wireworms are click beetles, so named because their elongated bodies are capable of producing a clicking sound. Only the larval stage causes damage.

DAMAGE

Wireworm larvae injure crops by devouring seeds in the soil, thus preventing seedlings from emerging. They also cause damage by cutting off small, underground stems and roots and by boring into larger stems and roots. Dig around the plant and look for wireworm larvae to confirm that they are the cause of injury.

MANAGEMENT

Wireworms may be a problem following an alfalfa rotation or in fields that were previously pastures. Cultivating, flooding, and dry fallowing can help reduce wireworm numbers.

Monitor for the presence of wireworm larvae by burying carrot pieces partially into the soil prior to seeding in order to attract the wireworms. If wireworms are present, a preventive seed treatment such as thiamethoxam may be necessary.

Start inspecting plants for wireworm damage when the crop emerges. Often the wireworm will be found near the damaged or missing seed or plant. Use treated seed in fields with a history of wireworm problems.

Common name Amount per acre** REI‡ PHI‡
(Example trade name)   (hours) (days)
Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used.
 
A. IMIDACLOPRID
(Admire Pro-soil) 7.0–10.5 fl oz 12 21
MODE-OF-ACTION GROUP NUMBER1: 4A
COMMENTS: Apply to soil or chemigate. Apply before or at planting when monitoring suggests wireworms could be a problem.
 
SEED TREATMENT
 
A. THIAMETHOXAM
(Cruiser 5FS) 1.28 fl oz per 100 lbs seed NA NA
MODE-OF-ACTION GROUP NUMBER1: 4A
** See label for dilution rates.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment until harvest can take place.  In some cases, the REI exceeds the PHI The longer of these two intervals is the minimum time that must elapse before harvest may take place.
1 Rotate pesticides with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; pesticides with a 1B group number should be alternated with pesticides that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Dry Beans
UC ANR Publication 3446

Insects and Mites

R. F. Long, UC Cooperative Extension, Yolo County
P. B. Goodell (emeritus), UC IPM Program

Acknowledgment for contributions to Insects and Mites:
L. D. Godfrey, Entomology, UC Davis

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