298 C. H. TURNER. 



naturalists, very little attention has been paid to their death- 

 feigning behavior. Emerton (6) asserts that rough handling 

 caused his specimens to remain inactive for a time, and Mac- 

 Lachlan (n) states that the form observed by him letisimulates. 

 Each of these students dismissed the matter with a single 

 sentence. 



The results recorded in this article are based on a careful 

 laboratory study of 100 individuals selected at random; supple- 

 mented by observations made in the field. About 60 per cent, 

 of these came from Kansas; the remainder from the vicinity of 

 St. Louis, Mo. Some were quite small and others were almost 

 large enough to form their cocoons. They were isolated in 

 numbered jelly-glasses, partly filled with loamy loess, and were 

 kept in an out-of-doors insectary, the north wall of which was 

 constructed of wire netting. The other walls were opaque. 



Any stimulus which produces a shock will usually cause an 

 ant-lion to letisimulate. Rough handling, roughly turning it 

 upon its back, dropping it from a slight elevation, all have a 

 similar effect. I usually induced the feint by roughly turning 

 the larva upon its back, or by dropping it from a slight elevation. 

 Occasionally I found an individual that I could not induce to 

 letisimulate; but this was a very rare occurrence. 



Several investigators have thought it important to determine 

 if the poses of letisimulating individuals are death attitudes. 

 Based on a consideration of seventeen species of invertebrates, 

 Holmes (31) concludes that the poses assumed were usually quite 

 different from death attitudes; although there were some species 

 in which they were always identical. I find that the ant-lion 

 has not one, but several death attitudes; likewise it possesses a 

 number of death-feigning postures, some of which resemble a 

 death pose and some of which do not. The insect suddenly 

 becomes rigidly immobile in whatever attitude it may be when 

 it receives the shock. Absolute immobility is the character that 

 is common to all cases; when the feint follows a long period of 

 fasting, this inactivity often simulates death. The rigidity, 

 however, is not so great as that described for certain insects. 

 In some species of insects the rigidity of the parts during a death 

 feint is so great that the insect may be picked up by a tarsus and 



