Vol. XXXl] ENTOMOLOGICAL NEWS 147 



mented the cataract, that the nests soaked with water broke up and were 

 abandoned. " 



A list of more than 120 titles of books and papers bearing on wasp 

 activities closes the 'Studies.' P. P. CALVERT. 



SOME HABITAT RESPONSES OF THE LARGE WATER-STRIDER, Gerris 

 remigis Say by C. F. CURTIS RILEY. American Naturalist, vol. LIII, 

 No. 628, pp. 394-414, 1919; vol. LIII, No. 629, pp. 483-505, 1919; vol. 

 LIV, No. 630, pp. 68-83, 1920. The late Dr. C. Gordon Hewitt in his 

 presidential address before the members of the American Association of 

 Economic Entomologists at their 29th annual meeting in 1916, called 

 attention to insect behavior as a factor in applied entomology and to the 

 need of further work along such a fundamental line. Papers on insect 

 behavior are not common in entomological journals and for this reason, 

 attention is hereby called to Prof. Riley's series of papers in The American 

 Naturalist. These treat of certain habitat responses of apterous forms of 

 the large water-strider, Gerris remigis Say, the observations and experi- 

 ments having been made in Illinois and New York. Various observations 

 are recorded on the responses of water-striders trapped in stream pools 

 during a period of severe drought. It was found that during a severe 

 drought, as food became scarce or when a scum formed on the surfaces of 

 some pools, the gerrids migrated by way of the riffles to pools that were 

 free of scum. As the drought progressed the striders congregated on the 

 few pools that remained. After the pools dried up, the insects left them 

 after a short length of time but not immediately and sought other pools. 

 Frequently, shade and lower temperatures induced the gerrids to stay 

 quietly but temporarily beneath clumps of dead leaves, stones, etc. They 

 did not aestivate Riley states that the gerrids appeared to find other 

 pools by a blundering method of trial and error. 



Fifty percent of a total number of gerrids entrapped on the surface of 

 a certain stream pool were successful in reaching \vater elsewhere ten 

 yards away. On other occasions much smaller percentages were able 

 to find water after the pools on which they were confined had become 

 dry. In some cases the water was less than ten yards away and in others 

 it was eleven, twelve and fourteen yards distant. During periods of 

 long and severe droughts it is believed that large numbers of apterous 

 individuals die. Various experiments were performed for the purpose 

 of finding out whether water-striders were able to reach their habit.it 

 after having been removed from it and placed on the ground certain 

 distances away. Individuals were headed away, toward and parallel 

 to the water and in all cases up to certain distances, the majority <>t tin- 

 insects reached the water. An experiment to discover whether moisture, 

 vision, or both factors functioned as stimuli in influencing the water 

 striders to find the brook was inconclusive, due to the failure ol tin- bar- 

 rier to shut off the view of the stream and this is the only defect, it it < m 



