416 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
A few other insects have occasionally been found to feed on the 
chinch-bug but it has been generally supposed that predaceous insects 
are only a very slight check on its increase. 
During the recent outbreak of this insect in Illinois (1909-1915) a 
number of observations on its predaceous enemies were made by the 
writer while conducting experiments on methods of chinch-bug control. 
In the summer of 1915 a number of insectary experiments were made 
to learn just how many chinch-bugs the more abundant of these 
predaceous insects would eat, and how common they were in the field. 
Those most commonly found feeding on the chinch-bug throughout 
the infested area in Illinois were adults and nymphs of the damsel bug, 
Reduviolus ferus, larvae of Chrysopa and Hemerobius, adults of the 
small ground beetles, Blechrus glabratus and B. pusio, nymphs and 
adults of Pagasa fusca, larvae of several species of Coccinellidae, and 
nymphs and adults of the common flower bug, Triphelps insidiosus. 
The ground beetles most common in infested fields were not found 
to feed on chinch-bugs to any extent. Casnonia pennsylvanica ate 
small numbers of them and Agonoderus pallipes ate dead bugs and 
molt skins. Ants were never observed to attack living chinch-bugs 
in the fields although they would do so when the bugs approached an 
ant nest. Several of the species common in cornfields were noticed 
carrying dead bugs. Cincindelid adults were seen to eat small num¬ 
bers of chinch-bugs along barrier lines. 
The following notes give the detailed results of the studies of the 
above mentioned insects. In these experiments single specimens of 
the predaceous insects to be tested were placed in clean vials with a 
known number of chinch-bugs of known stages of growth. A few 
sections of foxtail grass were also placed in the vials as food for the 
chinch-bugs, and the vials stopped with cotton. These vials were 
examined daily and fresh food for the chinch-bugs added and fresh 
bugs as needed. By the use of check vials in which only chinch-bugs 
were confined, it was found that they could be kept in a normal state 
of growth in this way, several lots being carried through from egg to 
adult. 
Chrysopa oculata and C. rufilabris. Chrysopa larvae were abundant 
in all fields of grain infested by the chinch-bug. They were often seen 
feeding on chinch-bug nymphs especially in cornfields where they 
would be found behind the boots of the lower leaves where the chinch- 
bugs were most abundant. In a number of cases chrysopa larvae were 
seen to suck from three to five chinch-bugs in the course of ten minutes. 
The insectary experiments were first started with chrysopa larvae col¬ 
lected in the field in different stages of growth, but were later carried 
on with larvae hatched from eggs in the insectary. 
