Mimeo E-39
November 1951
Rev. January 1956 (3M)
Purdue University
Agricultural Extension Service
Department of Entomology
WIREWORM CONTROL
In many areas of Indiana, wireworms are common and destructive pests of com, potatoes, tobacco, beans and sometimes other crops. Injury is most severe in poorly drained areas and in low, wet spots in the field.
Wireworms damage com in a number of ways. They may destroy the seed before it germinates or feed on the tap roots of the young plants, causing them to die. They also bore into the stalks just below the ground level, causing the plants to die at an early age. During the growing season, they continue to feed upon the roots, but the corn will usually survive this type of damage. Infested areas are characterized by thin stands with many missing plants.
The worms can be found by digging around sickly plants or into hills where the seed has failed to germinate. They damage potatoes by boring into the tubers and tobacco by working in the stems. Control for tobacco wireworms is given in Purdue Mimeo E-43.
ADULT	LAR
(About 4 times natural s
Wireworms are hard, slender, smooth, brown worms ranging up to about 1 inch in length. They are the larvae of the familiar "click beetles" or "snapping bugs". There are many different species occurring in Indiana, most of which require from 2 to 5 years for the worms to complete their growth in the soil. The eggs are laid in low, grassy or weedy areas and the heaviest infestation probably occurs in sod lands that have remained undisturbed for a number of years. Damage to cultivated crops is most severe the first and second years after such sod is broken and diminishes thereafter with the continued growth of cultivated crops. When the land is returned to sod, even for a single year, some reinfestation will take place. Also, eggs are laid under cultivated conditions, so that fields may never be entirely free of wireworms.
It should be pointed out that some soils never have enough wireworms to be concerned about; therefore, the best guide to determine if control measures are needed is the past history of wireworm damage in the field.
CONTROL MEASURES
Wireworm populations in soil can be decreased and often reduced to insignificant numbers by drainage of low areas. Drainage has not given complete control on muck soils nor on some mineral soils. In recent years, several of the new insecticides have been found to give excellent wireworm control. They have been tested and used as seed treatments, broadcast treatments, and as band treatments combined with a starter fertilizer.
Seed Treatment for Com
Experience with seed treatments for com has shown that they will give good results when used on soils having a low to average wireworm population. In the case of high populations, the insects may kill the young plants after germination, and under such circumstances, the band or broadcast treatments are preferred.
Seed treatments on com can be applied as either a slurry or as a dust. Diel-drin has given the best results as a seed protectant and can be obtained as either a 50 percent wettable powder or in combination with a fungicide. The wettable powder is applied dry at a rate of 3 ounces for each bushel of seed. The powder must he thoroughly mixed with the seed in such a manner as to insure a thin coating of powder on each kernel. The dieldrin slurry can be applied by the seed processor the seed is prepared for storage or by the farmer immediately before planting. Directions of the manufacturer should be carefully followed in applying the slurry.
It is important to remember that all seeds must be coated and then allowed to dry before planting time.