A BIBLIOGRAPHY OF THE NORTHERN CORN ROOTWORM 
AND THE WESTERN CORN ROOTWORM 
W.H. Luckmann, H. C. Chiang, E. E. Ortman, and Martha P. Nichols 
_ THIS BIBLIOGRAPHY is limited to papers dealing with 
the northern corn rootworm, Diabrotica longicornis 
(Say), and the western corn rootworm, Diabrotica 
virgifera LeConte. The 426 titles in the present list were 
obtained primarily from standard reference sources and 
the personal files of the authors. 
The northern corn rootworm and the western corn 
rootworm are major pests of corn in the corn belt region 
of north-central USA. Distribution extends beyond this 
area, but damage by the larva is usually negligible south 
of latitude 30° N. The northern corn rootworm is most 
ibundant in North America in an area roughly extending 
rom latitude 37° to 45° N and longitude 80° to 100° W. 
[he western corn rootworm is dispersing to the east and 
t is currently most abundant in an area roughly extending 
rom latitude 40° to 45° N and longitude 85° to 105° W. 
Numerous isolated infestations of each species occur be- 
yond these general boundaries south to the Mexican 
order and into Ontario, Canada, with new infestations 
eported each year. The two species are indigenous to 
North America. 
The western corn rootworm is a product of modern 
igriculture. It intensified as a problem in irrigated corn 
n Nebraska about 30-40 years ago. Up to 1955, the 
vestern corn rootworm was found only in Nebraska and 
vortions of Colorado, Kansas, South Dakota, and western 
owa. Since then it has moved eastward and northward 
nto major corn-producing states. It developed resistance 
0 the cyclodiene soil insecticides in the 1950’s and the 
listribution of the resistant strain expanded northward 
ind eastward. 
The biology and behavior of the two species are very 
imilar. In nature, corn is probably the only host, though 
t has been shown experimentally that the immatures of 
10th species can develop to varying degrees on certain 
ther species of grasses. Adults feed on the pollen, silks, 
nd kernels of corn and on the fruiting structures of many 
ither plants, including weeds. 
The northern and the western corn rootworms have 
nly one generation per year. Most eggs are laid in August 
a the soil in cornfields. The eggs are usually concentrated 
1 the rows at the base of the corn plants in nonirrigated 
elds and between rows in fields with irrigation. Most 
ggs of the northern corn rootworm will be deposited in 
ae upper few inches of soil. Ovipositional behavior of 
he western corn rootworm is slightly different, as females 
viposit many of their eggs between the plant rows and 
This peper, in the Biological Notes series, is published with special project 
inds. Dr. W. H. Luckmann is head of the Section of Economic Entomology 
- the Illinois Natural History Survey, and Professor, Illinois Agricultural 
xperiment Station. Dr. H. C. Chiang is a Professor of Entomology at the 
‘hiversity of Minnesota. Dr. E. E. Ortman is Head of the Department of 
ntomology, Purdue University. Martha P. Nichols is a Research Associate, 
‘ternational Programs and Studies, University of Illinois. 
. 
eggs are often deposited at a greater depth in the soil. 
Following oviposition, eggs develop slightly and diapause 
through fall and winter. In the corn belt area of the USA 
the eggs begin to hatch in June and the first adults ap- 
pear in July. Some eggs will not have hatched by the time 
the first adults appear. Thus, the egg stage lasts about 10 
months, although, experimentally, a few eggs of the 
northern corn rootworm have been shown to go through 
two winters. 
The larvae feed on corn roots and concentrate near 
the base of the plant. The larvae consume the roots, 
decreasing nutrition supplied to the ear, and in strong 
wind and rain storms plants with moderate to severe 
root damage may become lodged. The duration of the 
larval plus pupal stages is about 1 month. In laboratory 
cages, adult rootworm females will live about 2 months 
and oviposit for about 3 weeks, during which time they 
will deposit about 300-350 eggs. In the field, adult life 
probably does not exceed 5-6 weeks. There is a pre- 
oviposition period of 2—2% weeks. Northern corn root- 
worms are very difficult to maintain in the laboratory, 
and culturing has not been very successful. The western 
corn rootworm can be cultured in the laboratory, but the 
egg diapause does not permit continuous mass rearing. 
The adults may remain for a considerable time in the 
field where they emerge. Later they disperse, seeking 
pollen in late-maturing fields, alfalfa, and ornamental 
plants. Northern corn rootworm adults congregate on 
silks and in tips of ears of corn, whereas western corn 
rootworm adults have less tendency to congregate and 
they will be found on other parts of the plant as well as 
the ears. Thus counts made in ear tips will show a pre- 
dominance of northern corn rootworm adults, whereas 
casual visual counts in the same field and at the same 
time show a predominance of western corn rootworm 
adults. 
Northern corn rootworms and western corn rootworms 
live together and have similar habits, and there is some 
interaction between the two species. Several researchers 
have reported a displacement of the northern corn root- 
worm by the western corn rootworm. Interspecific 
matings have been observed in the fields, and F; progeny 
of crosses were produced in the laboratory. The F, adults 
have the phenotype of the western corn rootworm. 
Larvae of northern corn rootworms and western corn 
rootworms are resistant to the cyclodiene insecticides over 
much of their range. Organophosphate and carbamate 
soil insecticides applied at planting time are used for 
control. Rotating corn with other crops is a positive 
means of control. Usually, only the larvae are damaging, 
but adults congregating and feeding on fresh silking ears 
