30 
Psyche 
[March 
experimentals were eating the tissues of the exposed larva. 
Next a decapitated Encoptolophus sordidus Burm. was 
placed in the jar. Its metathoracic legs were removed to 
prevent kicking. The grasshopper was investigated by the 
larvae but no attack made upon it ; however, when the carcass 
was slit open, the larvae that chanced upon it started feeding 
almost immediately. The flesh, the eggs contained within 
the abdomen, and as much of the cuticle as was not too 
heavily sclerotized were eaten. At this stage the small 
pupating arctiid was also eaten by the /. isabella. 
It can be seen from these observations that larvae are 
more readily attacked and eaten when their tissues are 
exposed. It is to be expected that caterpillars would be 
more attracted to exposed tissues because there is a more 
concentrated odor arising from them than from an insect 
completely sheathed in cuticle. Also, there is no stimulation 
of the mouthparts by an unmutilated carcass. On the other 
hand, body juices exposed to the air may stimulate the 
mouthparts directly. Further there is the possibility that 
larvae partaking of body juices are prompted to do so by 
thirst. An unmutilated carcass is attacked only when the 
larvae reach such a degree of starvation that they bite fre- 
quently at near-by objects. 
In order to ascertain the exact series of events occurring 
when an animal with cannibalistic or carnivorous tendencies 
approaches another larva, a single live naked noctuid larva 
was placed in the jar with one E. acred. In the limited area 
the two frequently encountered each other. The E. acrea 
had reached the stage in which it bit at all objects encoun- 
tered. When it endeavored to take several bites of the 
noctuid, however, the latter thrashed about vigorously. 
Although the arctiid stabbed viciously at its intended victim 
several times, it finally withdrew. The noctuid’s cuticle had 
not been pierced. On numerous occasions the same process 
was repeated. Finally the noctuid was rendered more or 
less quiescent by the buffeting of the more active and ag- 
gressive arctiid. In this quiescent state, more or less bathed 
in its own regurgitated juices and those of its attacker, the 
noctuid was eaten. Undoubtedly this procedure takes place 
in most instances when one live insect is eaten by another. 
The higher percentage of cannibalism noted under crowded 
