1923] 
A Singular Habit of Sawfly Larvae 
9 
A SINGULAR HABIT OF SAWFLY LARViF 
By W. M. Wheeler and W. M. Mann. 
The following casual observations made in two widely 
separated South American localities seem worth recording as 
we have been unable to find any published account of similar 
behavior among the larvae of New World sawflies. 
July 16, 1920, the attention of the senior author was at- 
tracted to a very conspicuous, compact mass of sawfly larvae 
crawling like a hugh slug over the short grass and sandy soil 
along the side of a trail through the jungle near Kartabo, British 
Guiana. The mass was about ten inches long, four inches broad 
and two inches thick in the middle. It was elongate elliptical 
and rather pointed at each end and retained its shape and size 
unaltered as it progressed like a single organism over the sub- 
stratum. It consisted of about 200 larvae, each an inch long and 
of a deep metallic blue color (Fig. 1). Further investigation of 
of this singular mass was cut short by a heavy tropical shower. 
A number of the larvae were hastily thrown into a vial of alcohol. 
Although the senior author hoped to find the larvae in the same 
locality under conditions more favorable for study, they were 
not again encountered either by him or by any of the other 
workers at the Tropical Laboratory. 
The junior author had occasion to study a migrating mass 
of the same or of a closely related sawfly larva during February 
1922, on the forest trail between the Mission and the edge of the 
pampa, near Cavinas on the Rio Beni, in Bolivia. The mass 
which he encountered was about a foot long, three or four inches 
broad at the middle, narrowed in front and behind and thickest 
in the middle. It, too, consisted of more than a hundred dark 
metallic blue larvse of the same size as those observed by the 
senior author. The mass was also moving along as a compact 
unit and from a distance looked like a gigantic Planarian. When 
a pair of forceps was thrust into the midst of the larvse and a 
number of them thrown out to the side, those in front and behind 
