ANATOMY OF THE TOMATO-WORM LARVA, 
PROTOPARCE CAROLINA.* 
By ALVAH PETERSON. 
The larve of Protoparce carolina are excellent subjects for 
the study of the anatomy of a developing insect. Its size and 
abundance during the late summer and early fall make it an 
available subject throughout the middle west. There are no 
detailed investigations of the larva of this family, so that a 
discussion, such as is given in the following pages, would not 
seem out of place. This investigation was started under Dr. A. 
D. MacGillivray, in order to acquire some intormation as to the 
internal anatomy of insects. Since there is such a dearth of 
literature dealing with the larve of American Lepidoptera, I 
have prepared, at his suggestion, the following descriptions 
and figures. I am greatly indebted to Dr. MacGillivary for 
suggestions and other help. I have found Mr. A. G. Hammer’s 
excellent paper on the nervous system of the larva of Corydalis 
cornuta L. very useful and wish to express my appreciation of it. 
METHODS. 
When the work was first taken up, it was doubtful if it 
could be completed in one season, for only a hmited amount of 
good material was available. There still remain a few points 
that need further observation, and these will be mentioned later. 
The best material for dissection proved to be larve that had 
been killed in hot water and preserved in 70% alcohol. Even 
with the largest and the best prepared specimens, one finds that 
the internal structures are not as easy to follow as one might 
expect. Especially is this true with respect to the nervous and 
circulatory systems. The factor causing the greatest difficulty 
outside of the frailty of the material, is the existence of a super- 
abundance of adipose tissue or fat. To remove this fat, without 
tearing or destroying other parts, in order to observe the 
various organs, is difficult. The larvae were opened by cutting 
a longitudinal slit along the meson on the dorsal or ventral 
aspects and laid out flat and pinned in dissecting trays. By 
gently rubbing and teasing the masses of adipose tissue, one 
can remove a sufficient amount to be able to observe the covered 
*Contribution from the Entomological Laboratories of the University of 
Illinois, No. 31. 
246 
