December, '14] FLINT: LASIUS AMERICANUS 477 



of this species was being watched by the aid of a red carbide lamp. A 

 back-swimmer (Notonectid) happening to alight among several Lasius 

 workers, one of the ants at once seized the back-swimmer by one of its 

 legs. In a few seconds twenty or more ants were crowded about the 

 insect, many holding to it, and in less than two minutes it had been 

 dragged into the Lasius nest. During the next few minutes the ants 

 killed a number of small Jassids that, attracted by the lamp, alighted 

 among them. Often an ant would capture a Jassid as large as itself 

 and carry it into the nest. 



On this and other warm nights when the ants were very active, a 

 number of living insects were placed near their nests, and in nearly 

 all cases these were quickly caught and killed. If at first only a few 

 ants were on the ground near the nest entrance and a small insect such 

 as Diabrotica longicornis was dropped among them, as soon as the ants 

 on the surface began to struggle with the beetle, others would come 

 out of the nest in such numbers that several hundred would sometimes 

 be gathered about the entrance. When a large number were assembled 

 in this way, they would attack and kill insects of considerable size, 

 Diabrotica 12-pimctata, D. longicornis, and Agoiioderus pallipes were 

 readily killed. The ants seem to be especially fond of the last-named 

 beetle for food, as they may often be seen dragging it to their nests. 

 Heliothis obsoleta larvse, nearly full grown, were killed after a short 

 struggle; and even adult Epicautas, both E. marginata and E. vittata, 

 were killed after a hard struggle, as were also many small beetles and 

 moths. Lasius does not, however, seem able to kill Pentatomids of 

 any size. Insects of this family were frequently dropped among the 

 ants, but always escaped if not first injured. Even when killed they 

 were seldom dragged within the nest, and it would seem that the 

 odor of these insects is offensive to the ants. 



One point of considerable interest was the manner in which the ants 

 caught the insects. In very many cases they would seize their prey 

 by the legs and hold them in this way until killed by the bites of other 

 ants on the head or abdomen; but more frequently an ant would get 

 on the back of its victim and hold it by the antennse until killed by 

 other workers. In some cases an insect would take flight and carry 

 the ants, hanging to its legs, for some distance. The effect of the 

 ant bites must have been very poisonous to most of the insects killed, 

 as Diabrotica longicornis was often killed in thirty seconds, Agonoderus 

 pallipes in a minute or less, and other larger insects in a surprisingly 

 short time. It was very evident that when very active Lasius ameri- 

 canus will attack any insect that happens near its nest; and, while 

 many escape, the total number killed by these ants in the course of a 

 season must be very large. 



