254 



BULLETIN OI^ THE BUREAU OI^ FISHERIES. 



The images are found in large numbers around the ponds, but stick to the vegetation and do not 

 fly out over the water. The nymphs were found in all of the ponds; and nympb skins were present 

 in all the counts. 



SYMPETRUM CORRUPTUM (Hagen). 



Mesothemis corrupta Hagen, Synop. Neurop. N. A., 1861, p. 171. 



Appears early in the season and is common around the ponds; then dkninishes gradually and by 

 the middle of August entirely disappears. 



Nymphs were found in all the ponds, and nymph skins occurred in the first two counts. It is the 

 largest species of the genus and the strongest flyer, going out, like other dragonflies, over the water, 

 but never in numbers, and remaining but a short time. 



ERYTHEMIS SIMPLICICOLLIS (Say). 



Libellula simplicicollis Say, Jour. Acad. Nat. Sci., Phila., 1839, P- 28. 



Second in abundance at the ponds, sticking close to the grass and weeds and never taking long 

 flights. It does not perch on the sides of the grass stems like L. luctuosa, but prefers a horizontal blade 

 of grass and settles down flat upon it. The females hunt almost exclusively in the grass and feed upon 

 diptera, small butterflies and moths, and damselflies, especially teneral Enallagmas and Lestes (PI. 

 LXIX, fig. 2.) 



Williamson (1899, p. 326) has noted a peculiar habit of the males. Two of them hover over the 

 surface of the pond close to the water, one a few inches above and in front of the other. The lower 

 one then rises in a curve over the back of the upper one, which at the same time moves in a curve down- 

 ward, backward, and then upward, so that the positions of the two are exactly reversed. The two keep 

 this up for several minutes and then separate; such movements may be witnessed on any clear day 

 by watching for it. 



The two sexes never fly about together, but the female oviposits alone, hovering close to the water 

 and repeatedly dipping the tip of the abdomen beneath the surface. Both sexes alight on the floating 

 algae and other water plants, unlike most dragon flies. 



The nymphs never crawl far from the water to transform, and many of the skins are found upon 

 rush stems standing in the water. They showed a curious preference for Carex stricta and Homalo- 

 cenchrus oryzoides, and but very few skins were found on other plants. Such a preference was probably 

 due more to the position of the plants than to any other factor. The two sexes are shown in Plate 

 LXIX, figure i. 



PACHYDIPLAX LONGIPENNIS (Burmeister). 



Libellula longipennis Burmeister, Handb. Entomol., vol. 2, 1839, p. 850. 



Not very common around the ponds, although a few can be found there all through the season. 

 The matured, pruinose males are more in evidence than the females; both sexes have the habit of droop- 

 ing the wings and elevating the abdomen when they alight. Nymphs were more abundant in ponds 

 2 and 3, and nymph skins more numerous in July and August. 



LIBELLULA LUCTUOSA Burmeister. 



Libellula luctuosa Burmeister, Handb. Entomol., vol. 2. 1839, p. 861. 



This is by far the most common species at Fairport and can be recognized by the broad, black 

 bands across the wings, with chalky white spots outside of them in the male. It is very energetic and 

 active, but alights often upon the grass and sedges and sometimes remains at rest a long time. It does 

 not hover after the manner of some species and does not hunt late at night, being rarely seen actively 

 flying about after sunset. It roosts in the tall grass up in the fields, holding onto the grass stem well down 

 out of sight, and sometimes in the vegetation alongside of the ponds. Its characteristic attitude is to 

 grasp the stem with all six legs, the longer hind legs holding the body inclined at an angle of about 45° 

 with the stem, as shown in Plate LXVIII, figure 2. It gets thoroughly wet with the dew during the 

 night and does not start flying in the morning until the dew has dried off. 



The two sexes do not fly about together after the manner of Anax, Tramea, and Celithemis, but the 

 female oviposits alone, dropping her eggs loosely in the water, and not inserting them in the tissue of 

 an}^ water plant. 



