11 



able that Walsh's statements were based on insufficient data. 



The imagos usually keep near their nymphal home. The 

 Zi/(/opf('rff both fly and alight low, usually over water; the 

 stronger .Esr/niidft fly high and scatter more; while the other 

 imagos are diversified in these respects, many species being 

 taken both along streams and along borders of roads and fields 

 at some distance from water. 



All dragon-flies are most active in hot, quiet, sunshiny 

 weather. They cease flying by sunset, except a few of the 

 y£scJn/i(I((% which may be seen in hot pursuit of small D/pfera 

 during the evening twilight. 



The history of the order as a whole in the vicinity of 

 Havana, while under our observation, is interesting but some- 

 what puzzling. In 1894 there was a great abundance of indi- 

 viduals, m all stages. In 1895 the season's collecting opened up 

 well. Extremely low water prevailed, however, and in June the 

 shallow waters became greatly heated by the sun, their recorded 

 temperatures reaching as high as 96° Fahr. On one occasion, 

 when the heat of the water was especially noticeable, a num- 

 ber of dead nymphs were found floating about, along the west 

 shore of Quiver Lake. Not many nymphs were seen in the usual 

 situations at the close of this season, and from that time on 

 through 1896, they were reduced to insignificant numbers. The 

 low water of 1896, however, encouraged the development of spe- 

 cies liking swampy situations, and there was consequently in 

 1896 an excessive development of Pavhiidipbtx longipenni^ and 

 species of Sj/tHpcfnuH. A slight rise took place in the spring of 

 1896 and the river became very foul. At the close of the year the 

 drouth was broken, with a more extensive rise of the river, and 

 the season of 1897 showed an increase in the number of nymphs. 

 The winter and spring following brought much high water in 

 the river, but the nymphs did not greatly increase in numbers. 



Kellicott has noted ('97a ; 97, p. 69) that in Ohio the warm 

 rainy weather of April, 1896, following the drouth of 1894-95, 

 caused emergence earlier than usual, and the number appear- 

 ing did not seem noticeably reduced by the drouth. 



