AGRICULTURAL EXPERIMENT STATION
of The Alabama Polytechnic Institute, Auburn, Ala.
E. V. SMITH, Director . . .
Control Of Soil Insect Pests
In Gulf Coast Irish Potato Fields
W. G. EDEN, Entomologist
F. E. GARRETT, Assistant in Horticulture
W IREWORMS and the imported fire ant are serious
pests of the Irish potato crdp in the Gulf Coast
Area of Alabama. The wireworm attacks both the seed
pieces after planting, and potatoes after they are set
on the plants. Damage to seed pieces results in re-
duced stands or lowered plant vitality. Wireworm
punctures in market potatoes can lower the grade or
keeping qualities. The imported fire ant reduces
stands by feeding on the tender seedlings, or lowers
the grade of market potatoes by feeding on them;
however, the most obvious ant problem is its painful
sting to persons picking up potatoes during harvesting
operations.
Experiments on the control of wireworms and the
imported fire ant in Irish potatoes were begun in 1955.
Control measures reported here are based on results
from these experiments.
WIREWORMS
Wireworms are immature forms of the common
click-beetle or skip-jack. The species found most
frequently in potato fields of the Gulf Coast Area of
Alabama is the Gulf wireworm, Conoderus amplicollis
(Gyll.). Adult beetles are approximately 3/8-inch
long and 1/8-inch wide. They are dark brown and
have a velvety appearance.
The life cycle of the Gulf wireworm is completed
in 1 year. Adult females deposit their eggs on or near
the surface of the soil during May and June. The eggs
hatch in 8 to 10 days, depending on temperature.
Young larvae begin feeding immediately and attain
most of their growth in 8 or 10 weeks. By the end
of November the larvae are almost fully grown and
very little growth occurs from December to February.
Duration of the larval period is about 10 months. Full-
grown larvae are about 3/4-inch long and nearly
1/8-inch wide. They have hard, shiny, yellowish
brown bodies and dark brown or black heads. Pupation
occurs in an earthen cell in the top layers of the soil
during April, May, and June; length of the pupal
period is approximately 8 to 10 days. Adult beetles
emerge in May and June, with a small percentage
emerging in July. The life history of this insect was
determined by Cockerham and Deen
1 
during the period
of 1929-32.
IMPORTED FIRE ANT
The imported fire ant, Solenopsis saevissima v.
richteri Forel, was probably introduced into the United
States at Mobile, Alabama, about 1925. It is a mound-
building fire ant. An average mound is about 15 inches
in diameter and 10 inches high, and contains about
25,000 workers. The workers range from 1/8- to
1/4-inch long and are reddish to reddish black.
An ant colony begins wheh the queen digs an
underground chamber and starts laying clusters of
smooth, shiny white eggs. The eggs hatch in 8 to 10
days. The larvae are helpless, dirty-white grubs and
depend on the queen and workers for food. Larvae
that become workers pupate in 6 to 12 days; those
that become winged forms take a longer time to de-
velop. Adults emerge from the pupal stage in 9 to 16
days. The entire life cycle is completed in about 30
days.
CONTROL
Four insecticides-aldrin, chlordane, dieldrin and
heptachlor-gave excellent control of wireworms and
fire ants in potato fields in 1955 experiments. Each
insecticide was applied as an emulsion spray to the
soil after it was turned, but before disking prior to
planting. A mixture to treat 1 acre was made by mix-
ing 2 pounds of aldrin, dieldrin or heptachlor, or 4
pounds of chlordane with enough water to make 30
gallons of spray.
Counts of ant mounds were made just prior to
harvesting the potatoes. There were no fire ant colo-
nies in any of the treated areas, whereas the untreated
check areas had an average of 61 active ant colonies
per acre.
Cockerham, K. L. and Deen, O. T. "Notes on the life
history, habits, and distribution of leteroderes laurentii
(Guerin)." Jour. of Econ. Ent. 29 (2): 288-96. 1936.
Progress Report Series No. 60
December, 1955
Sample potatoes were taken at harvest time, and
examined individually 
for wireworm damage. 
All in-
secticidal treatments gave excellent control of wire-
worms (Table 1).
TABLE I. EFFECT OF INSECTICIDAL SOIL TREATMENT
ON WIREWORM DAMAGE TO IRISH POTATOES, CLEVERDON
FARM, BALDWIN COUNTY, 1955
Percentage of potatoes
Treatment -damaged by wireworms
No treatment 24.2
Aldrin, 2 lb. per acre 0.2
Chlordane, 4 lb. per acre 0.3
Dieldrin, 2 lb. per acre 0.5
HeptachIor, 2 lb. per acre 0.0
SUMMARY
1. Wireworms, primarily the Gulf wireworm, and
the imported fire ant are serious pests of the Irish
potato crop in the Gulf Coast Area of Alabama.
2. These insecticides at. the indicated rates gave
excellent control of wireworms and fire ants in 1955
experiments: aldrin, 2 pounds per acre; chlordane, 4
pounds per acre; dieldrin, 2 pounds per acre; and
heptachlor, 2 pounds per acre. In each case, the in-
secticide was mixed with enough water to make 30
gallons of spray.
3. The insecticides were applied as emulsion
sprays to the soil after it was turned, but before
disking prior to planting.