Wireworms or tobacco worms are the common name for many species of click beetle larvae that have very hard bodies, although some species have softer bodies. They are mostly a problem for large scale farmers, especially for tobacco growers, but can also appear in home gardens, window boxes, bluegrass lawns and even potted plants inside the home.
Wireworms also have a fondness for potatoes, corn, peanuts, carrots and soybeans. However, they are opportunistic creatures and will eat whatever they can get a hold of.
Wireworms are between 0.25 and 1.5 inches long, depending on the species. They come in various shades of ivory, yellow, orange, tan or light brown. They are clearly segmented, somewhat like a limb of the Michelin Man, and are smooth to the touch. They often have tiny heads, a wider body and then narrow to tiny tails.
Click beetles lay their eggs on plants or just under the soil around plants, depending on the species. Hatchlings burrow underground and hibernate through the winter, right near their food supply. Gardeners then graciously plant seeds while the hatchlings sleep so they will not have to travel far for food. Wireworms begin feeding on newly sprouted seeds as soon as the soil is warm enough for seeds to grow.
Some damage to foods that grow underground, such as carrots and potatoes, will not be apparent until the crop is harvested. If there is a strong enough infestation, there will be nothing to harvest. But if there are only a few wireworms in the area, the produce will be riddled with small holes.
Treatment for wire worms must be placed in the garden at least three weeks before seeds are planted. But it can be difficult to determine if your garden has a wireworm problem. Setting up some ground corn or flour in a seed hole and checking every couple of days for feasting wireworms lets you know if you have a problem that needs fixing.
By the time damage to the plants are noticed, the wireworms are well on their way to maturing into click beetles. Effective insecticides include diazinon, chlorpyrifos and lindane. Regular inspections of dirt around new shoots need to be checked for surviving wire worms.
If using commercial insecticides are not an option, make sure your garden attracts birds and spiders that love to eat protein-rich adult beetles or juvenile larvae. The larvae of lightning bugs will also prey on wireworms. Some gardeners even remove the worms by hand and then kill them. Pheromone traps for click beetle adults are another option.