92 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
attacked in force, an occurrence which I have never seen, they seem to 
me completely master of the situation. I found that when pupae were 
dropped among the ants, or placed upon the ground near their colonies, 
they were devoured in six or eight hours' time. Ants were often seen 
swarming upon larvae and pupae in their webs upon the plants, but in 
nearly, if not quite all such cases the larvae and pupae had been injured,, 
possibly by a bird. I have not been able to obtain any evidence that 
the ants destroy the young or eggs of Aletia. 
" Of the t wo species of ants observed, one (Dorymyrmex flavus McCook) 
is testaceous in color, timid, and very active. It runs after a caterpillar- 
upon the ground, but does not take good hold, and is invariably thrown 
off. It makes quite a large cavity below the mouth of its gallery, which 
is also a considerable aperture. A worm dropped into this cavity usu- 
ally disappears from sight for several minutes, but invariably makes its 
appearance again at the mouth. It finds great difficulty in getting out> 
even if not disturbed by the ants. Usually it is followed by a swarm of 
its enemies, and repeatedly falls back, but almost always gets away in 
the end. Several caterpillars were replaced five or six times and dropped 
out of sight in the galleries of strong colonies, and, although severely 
bitten and bleeding, they escaped at last. A few worms succumbed to 
the attacks of the ants after having been repeatedly thrown back. 
"The second species (Solenopsis xyloni McCook) is dark brown, smaller^ 
and less active, but much more courageous. It is often seen marching 
in columns, and makes long subterranean galleries just below the sur- 
face of the' ground, with numerous exits along its course, from which 
quantities of finely-divided earth are thrown out. It is much more ag- 
gressive than the first species, attacks a worm fiercely, and holds on with 
great pertinacity, but does not follow up the attack when once the cat- 
erpillar has made its escape. It has a very severe sting, which paralyzes 
the worm. The latter, however, recovers if not too badly bitten. Most 
worms, when stung behind the middle, appear to be unable to use the 
anal r^rolegs, but can usually spring away. Sometimes the worm is en- 
tirely paralyzed, yet, if rescued in time, recovers, and I have bred the 
moths from such individuals. Notwithstanding its powerful weapon, 
I do not believe this ant can destroy a larva unless favored by chance, 
or unless the attack is made by great numbers and upon the ground. 
After the caterpillar has webbed up and become helpless, both these 
species of ants are occasionally found to attack it. I select from numer- 
ous field notes the following in confirmation of the conclusions I have 
drawn : 
"August 25.— The ants do not seem to attack the young larvae and 
eggs of Aletia which were crowded on the leaves, and yet they (the 
ants) swarm under (lie netting and eat up pupae placed in jars or boxes 
on the ground. I think this a very fair test of the work done by the 
ants, since, with every condition favorable, they fail to clear off young 
larvie and eggs upon plants at the foot of which they have very strong 
colonies. 
