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Past Articles Library | Organic Pest Control | Wireworms in Vegetables

WIREWORMS

Wireworms, also known as click-beetles, burrow into and feed upon newly planted seeds and underground plant parts such as roots, bulbs, and tubers. The range of this pest is worldwide.

DESCRIPTION

Adults are elongated, brown or black beetles 1/3 to 1 inch (8 to 25 mm) long with fine lengthwise grooves on their wing covers. The adults are often called "click-beetles" because they make a sharp click when they flip onto their feet. Larvae are yellow to brown, leathery, jointed, and worm-like up to 2 inches (5 cm) long. The last body segment is forked or notched.

LIFE CYCLE

Adults lay eggs in plant roots in early spring; eggs hatch in 3 to 10 days. Larvae spend 2 to 6 years feeding near the soil surface while soil is cool in the spring and fall. They burrow deeper in hot weather and again in late fall. Mature larvae pupate in late summer. One generation every 2 to 6 years.

PLANTS MOST AFFECTED

A wide variety including gladiolus and other corms, and most vegetables. Small grains, potatoes, corn, onions, beans, peas, sugar beets, and carrots are particularly susceptible.

DAMAGE

Wireworm larvae damage crops and plants by feeding on germinating seed, young seedlings, corms or tubers, and stunting or killing plants. Damaged plants soon wilt and die, resulting in thin stands. Damage to seedlings may be so serious that replanting is necessary. They also tunnel and damage maturing tubers and bulbs. Wireworms are worst in the spring and fall in newly turned soil and for a few years after. Adults feed on leaves and flowers but cause little damage in comparison to their offspring.

WIREWORM CONTROL

Prevention:

1. Delay planting tubers and corms until soil warms up. Larvae prefer cool soils and dig deeper into the ground when temperatures rise.

2. Keep soil bare until planting time.

3. Crop rotation can help keep populations low.

Control:

1. Use beneficial parasitic nematodes such as Grub-Away Nematodoes which are more effective than other commercially-available nematodes. More Information about Grub-Away Nematodes

2. To destroy larvae, cultivate the soil weekly for 4 to 6 weeks in the fall and spring when they are most active near the soil surface.

3. Use raw potato or carrot pieces as bait. Cut a potato in half and run a stick through the middle. Bury the trap about one to 2 inches (2.5 to 5 cm) deep so that the stick stands vertically as a handle. Pull the traps out after a day or two and discard wireworms.