ADDITIONAL NOTES 



ON THE 



ANISOPTERA 



IN THE VICINITY OF MANCHESTER, N. H. 



BY KDWARD J. BURNKAM. 



The drought that prevailed during July and August, 1900, 

 was exceptionally severe in the vicinity of Manchester, and, fol- 

 lowing the unusually dry summer of 1899, exerted a marked 

 effect upon the later Dragonfiies. The individuals of the Gom- 

 phine and Corduline types, which emerge earl}- in the season, 

 were apparently as numerous as in other years ; but there was a 

 great decrease in the numbers of individuals of Aeschnines and 

 Libellulines. A few species of the latter subfamily, notably 

 lyibellula exusta and Plathemis trimaculata, were abundant, ap- 

 pearing by the middle of June ; but early in July the drought 

 had dried up the smaller streams and nearlj^ all the pools and 

 bogs. Even such bodies of water as Stevens' Pond and Eake 

 Massabesic were reduced several feet below their ordinary sum- 

 mer level, leaving great strips of marsh to dr}- and bake in tht 

 sun. The n3^mphs of Tibellula, Sj-mpetrum (Diplax), Eeuco- 

 rhinia, Aeschna and other late-appearing genera and species 

 must have perished by thousands. A few survived, however, 

 and when the fall rains had revived the brooks and refilled the 

 pools, a limited number of individuals were Hying about their 

 accustomed haunts, evidently belated and hastening to complete 

 their life-work with dispatch. 



In considering how these few surviving Dragonfiies came to 

 be hovering over streams which for six weeks had shown only 

 dry channels, we are easily tempted from the hard road of sci- 

 entific investigation to the alluring bypaths of speculation ; but 

 there are a few conditions which may be accurately ascertained. 



