How to Manage Pests

UC Pest Management Guidelines

Cotton

Wireworms

Scientific Name: Limonius spp.

(Reviewed 5/13, updated 5/13)

In this Guideline:

Description of the Pests

Wireworms are the soil-dwelling larvae of click beetles. They resemble mealworms and are slender, elongate, yellowish to brown with smooth, tough skin. The body is usually cylindrical, but flat on the lower side. There are six short legs close together near the head, and the tip of the abdomen bears a flattened plate with a pair of short hooks.

Damage

Wireworms destroy germinating seeds and tiny seedlings. Often the wireworm will be found near the damaged or missing seed or plant. Even if the damage does not completely destroy the plant, the feeding wounds may predispose the plant to seedling diseases.

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 population. If wireworms are present in the soil, a preventive seed treatment may be necessary.

Common name		Amount per 100 lb seed**	R.E.I.‡	P.H.I.‡
(example trade name)			(hours)	(days)
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, also consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
A.	CHLORPYRIFOS
	(Lorsban) 30 Flowable	5.5 oz	0	0
	SELECTIVITY: High
	PERSISTENCE: Pest: Moderate NE:2 Short
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: Slurry treatment with appropriate delinted seed fungicide. Toxic to fish, birds and other wildlife. Keep out of any body of water and off of the soil surface.
**	Mix with sufficient water to create a slurry.
‡	Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
1	Rotate chemicals 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; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
2	NE = natural enemies

PUBLICATION

UC IPM Pest Management Guidelines: Cotton
UC ANR Publication 3444

Insects and Mites

• L. D. Godfrey, Entomology, UC Davis
• P. B. Goodell, UC IPM Program and Kearney Agricultural Research and Extension Center, Parlier
• E. T. Natwick, UC Cooperative Extension - Desert Research and Extension Center, Imperial County
• D.R. Haviland, UC Cooperative Extension, Kern County and UC IPM Program

Acknowledgment for contributions to Insects and Mites:

• E. E. Grafton-Cardwell, Kearney Agricultural Research and Extension Center, Parlier
• N. C. Toscano, Entomology, UC Riverside

Top of page