224 THE CANADIAN ENTOMOLOGIST 



The duration of the feint may be momentary or it may exceed 

 a hour. There is little uniformity either in individuals of the 

 same species or in the same individual during successive feints. 

 I have never found any gradational relation between the duration 

 of successive feints, but Fabre found that in the beetle Scarites 

 gigas the duration increased with each successive feint. With 

 Tychius picirostris the longest feint may occur at any place in a 

 succession of feints, but the average duration of the earlier feints 

 is greater than that of those occurring later in the series. Turner 

 had the same results with the ant-lion, and Gee and Lathrop the 

 the Severins, and other workers have also failed to observe any 

 definite relation in the duration of successive feints. 



Most insects will feign again and again if stimulated. The 

 number of successive feints is, however, limited. An insect after 

 responding to a larger or smaller number of shocks will finally 

 refuse to respond further. If allowed to rest, however, it will again 

 respond. 



In some cases^ — a well known example is the golden-rod chry- 

 somelid Trirhahda canadensis — the insect may feign death on the 

 near approach of the collector; in others the feint is not normally 

 elicited until the insect is touched. Within the same species, how- 

 ever, the intensity of the shock seems to have no effect on the in- 

 tensity or duration of the feint. 



Both the collector and the economic entomologist have taken 

 advantage of the death feint. One of the best known cases in 

 which the economic entomologist enlists the aid of this instinct is 

 the destruction of the plum curculio by jarring the trees. Scott 

 and Fiske in an account of their work on the control of this pest 

 in a Georgia peach and plum orchard give a list of other insects 

 collected by jarring the trees for the curculio. This list includes 

 two hundred and sixty-nine species of Coleoptera representing 

 thirty-one families; seventy-one species of Hemiptera-Heteroptera 

 representing eleven families; and eight species of Homoptera repre- 

 senting three families. Other orders were represented, but the 

 numbers were so few that these insects were not listed. 



The advantage of the death feigning instinct to its possessor 

 is doubtful. When an animal resembles its surroundings in colour 

 or form, the ability to remain perfectly still makes it practically 



