DRAGONFUES AND DAMSELFLIES IN PONDFISH CUI.TURE. IQI 



curled up in the sun, half or three-fourths of an inch above the water. Twenty-five 

 such teneral Ischnuras were seen close to their exuviae upon the pond-lily leaves of pond 

 3 on the afternoon of July 28, 191 7, but not a single Enallagma. Nor have the exuviae 

 of the latter ever been found in such places around the Fairport ponds. 



The nymphs of Argia modsta putrida often crawl long distances over the land and 

 then up the trunk of a tree and are the only damselfly exuviae found in such positions. 

 This leads naturally to the second consideration. 



2. Distance Traveled. — The distance to which the nymphs crawl before trans- 

 forming varies greatly, not only for the different species, but also for different individuals 

 of the same species. Some nymphs, like those of Perithemis domitia and the two Sym- 

 petrums, were always found upon rush or grass stems standing in the water, often at 

 quite a distance from the shore. Others, like Anax, -^schna, and Erythemis, were 

 dose to the shore, sometimes over the water, and sometimes over the land, but never 

 very far from the water's edge. Lihelhda hwtuosa, Epicordulia, and Plathemis, on the 

 other hand, crawl much farther and sometimes go a long distance. In the first count, 

 I Plathemis, 5 Epicordulia, and 47 L. luctuosa crawled up the bank of the pond, across 

 the cinder road, up a dirt bank bordering the road, and into the grass field, the entire 

 distance being 50 or 60 feet. The other individuals of these species were all found 

 between the road and the water's edge. 



. 3. Lack of Protective Instinct. — ^While instinct may guide the nymph to the 

 shallow and sunny side of the pond, it apparently fails him in some other directions. 

 There were two red-winged blackbirds' nests in the cat-tails and crex grass on the shore 

 of pond 2, where the second count was made. Twenty-five nymph skins were taken 

 within a radius of 6 inches of one of these nests, three of which were actually fastened 

 to the sides of the nest itself, and seven were found within a similar radius of the other 

 nest. The young birds had only just left the nests and were still in the immediate 

 vicinity, so that some of the nymphs must have transformed while the nests were still 

 occupied. 



4. Relative Abundance of Species. — From the counts above recorded it appears 

 that L. luctuosa is the most abundant species, and also that it emerges before the others. 

 Its time of greatest abundance is during the last of June and the first of July, when it 

 constitutes over 90 per cent of the dragonfly fauna of the ponds. Although it keeps up 

 a good percentage and remains throughout the season more numerous than any other 

 single species, it quickly loses its relative predominance and steadily declines during 

 the latter part of the season, until by the middle of August it is only a little more 

 numerous than E. simplicicollis. 



On the other hand the latter does not begin to appear until luctuosa has reached its 

 maximum. It then rapidly increases, v/hile Itictuosa is decreasing, and its time of greatest 

 abundance is the latter part of July, following which it declines through August. 



Tramea, Anax, and iEeschna did not really begin to appear until the middle of July 

 and then steadily increased through the remainder of the season, until by the first of 

 September, together with Epicordulia, they were about the only species left. In 191 7 

 a very much larger number of Anax and ^Eschna exuviae were found early in the season, 

 by the last of June or the first of July; but the imagos were no more numerous than 

 during the preceding year, because they scatter immediately after emergence. Both 

 species must return to deposit their eggs either in the pond where they were hatched or 



