92 REPORT 4, UNITED STATES ENTOMOLO .ICAL COMMISSION. 



attacked in force, an occurrence which I have never seen, they seem to 

 me completely master of the situation. I found that when pup^e 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 larvaa and pupae in their webs upon the plants, but in 

 nearly, if not quite all such cases the larvce and pupse 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 two 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 prolegs, 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 the 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 

 larvae and eggs upon plants at the foot of which they have very strong 

 colonies. 



