Egg - Eggs of tobacco wireworm are white, spherical, and about 0.5 mm in diameter. Eggs of the southern potato wireworm are similar.
Larva - Newly hatched tobacco wireworm larvae are 1.5 mm long and white. Fully developed larvae are yellowish-brown and 14 to 19 mm long. Tobacco wireworm larvae can be distinguished from southern potato wireworm larvae because the tobacco wireworm's last segment terminates in a V-shaped notch rather than in the almost closed, oval notch of the southern potato wireworm.
Pupa - Tobacco wireworm pupae are first white, but later change to reddish-brown. They are slightly larger than the adults (about 12.7 mm in length). Southern potato wireworm pupae are also slightly larger than adults and change from white to creamy yellow.
Host Plants - Tobacco, corn, cotton, potatoes, and other crops are hosts of the tobacco wireworm. Irish potatoes are the preferred host of the southern potato wireworm; however, newly set tobacco seedlings, roots of sweet potato, corn seedlings, and carrot are also infested. Less frequently attacked are melons, beet roots, and strawberry fruits that touch the soil surface.
Damge - The tobacco wireworm and the southern potato wireworm are the most common of several wireworm species that attack the stems of newly set tobacco. Wireworms damage newly set tobacco plants by boring into and tunneling in the stalks. Some plants may be killed or stunted which results in the need to replant. The resulting irregular stand has plants of varying size and maturity. More management problems occur with topping, suckering, and harvesting. The amount of damage varies from year to year and from field to field depending on weather, transplants, soil type, crop rotation, etc. Wireworms are more commonly a problem in Coastal Plain soils, especially if the field has not been plowed during fall and winter, or if the field was planted to a winter cover crop. However, the use of a cover crop is usually warranted in terms of erosion control.
Life History - The tobacco wireworm overwinters in the larval stage in North Carolina. Most larvae begin to pupate in mid-May and adult beetles emerge in June and July. Eggs (average 240/female) are laid on or slightly beneath the soil surface. After hatch, larvae bore into and tunnel in the stalks of tobacco plants. In North Carolina, the life cycle requires about 348 days (egg, 10 days; larva, 315 days; pupa, 10 days; and adult preoviposition period, 13 days). One generation occurs each year, though a very small number of larvae may survive a second winter.
The souther potato wireworm also overwinters in the larval stage. Two generations of the southern potato wireworm occur per year in coastal South Carolina: a short cycle summer brood and a long cycle winter brood. Adult beetles emerge in May and June and again in late August and September. Summer-brood larvae infest plants throughout summer; whereas, winter-brood larvae are a problem in early fall and again in early spring.