How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PESTS

Wireworms are shiny, slender, cylindrical, hard-bodied, yellow to brown larvae that can be found at all times of the year and in almost any kind of soil. The larval (or wireworm) stage of this insect may last several years. When fully developed, they vary in length from about 0.5 inch to 1.25 inches (12–31 mm), depending on the species. Adults of these larvae are known as click beetles. They can snap and flip their bodies into the air when turned upside down. These tan to black beetles vary from 0.25 inch (6 mm) to more than 1.0 inch (24 mm) in length, but the most common pest species are about 0.5 inch (12 mm) long.

DAMAGE

Wireworm larvae injure crops by partially or completely devouring seeds in the soil, thus reducing plant stands. On plants, they can cut off small, underground stems and roots or bore into larger ones.

MANAGEMENT

Preventive treatment may be warranted for crops planted in land that was previously pasture or planted to alfalfa, vineyards and possibly grains. Otherwise, good field sanitation and measures to ensure rapid seed germination are generally adequate for control of this pest.

Cultural Control
Minimize plant residue from previous crops. Fallow fields for several weeks to allow organic matter to decompose. Seeds planted at depths greater than 1.5 inch (3.7 mm) take longer to germinate and are at greater risk for infestation. Do not plant into cold, moist soil.

Organically Acceptable Methods
Cultural controls are acceptable to use in an organically certified crop.

Monitoring and Treatment Decisions
If wireworms have been a serious problem in the past, a preventative treatment may be necessary. Preplant or seed treatments are far superior to any postemergent practice.

Common name		Amount/Acre	P.H.I.+
(trade name)			(days)
When choosing a pesticide, consider information relating to water quality and impact on natural enemies and honey bees.
A.	IMIDACLOPRID
	(Admire) 2F	16–24 fl oz	21
	MODE OF ACTION: A neonicotinoid (Group 4A)1 insecticide.
	COMMENTS: Apply at planting or transplanting and incorporate into root zone. Repeat applications of any neonicotinoid insecticide (imidacloprid-Admire; thiamethoxam-Platinum) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance.
B.	DIAZINON*
	(Diazinon) 14G	21–28 lb
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: Labeled for use on melons and watermelons only. Broadcast and incorporate into soil just before planting. May also control seedcorn maggot.
	(Diazinon) 50W	4–8 lb
	(Diazinon) AG500	2–4 qt
	COMMENTS: Labeled for use on melons and watermelons only. Broadcast just before planting and immediately work into the soil 4–8 inches.
C.	METAM SODIUM*
	(Vapam)	Label rates
	COMMENTS: Apply as a band treatment before planting. Fumigants, such as as metam sodium and 1,3-dichloropropene, are a prime source of volatile organic compounds (VOCs), which are a major air quality issue. Fumigate only as a last resort when other management strategies have not been successful or are not available.
+	Preharvest interval. Do not apply within this many days of harvest.
1	Modes of action are important in preventing the development of resistance to pesticides. 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. 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 is assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
*	Permit required from county agricultural commissioner for purchase or use.

PUBLICATION

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
R. L. Coviello, UC Cooperative Extension, Fresno Co.
E. T. Natwick, UC Cooperative Extension, Imperial Co.
L. D. Godfrey, Entomology, UC Davis
C. B. Fouche, UC Cooperative Extension, San Joaquin Co.
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
Acknowledgment for contributions to the insect and mite section:
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties

Top of page