224 



BUI.LETIN OF THE BUREAU OF FIvSHERIES. 



United States ever eats them. Shrikes, cuckoos, and kingbirds, however, catch and 

 eat the images, even after the wings of the latter have become fully hardened. Hence 

 they are active enemies during the entire adult life of the dragonfiies and cause con- 

 siderable destruction. 



3. Larger Imagos. — The imagos of the larger species are great enemies of the 

 smaller species; this is especially true of the gomphids, of Anax, and of Brythemis. 

 All of these were observed eating teneral damselflies and sometimes teneral dragonfiies, 

 and these seem to be the favorite food of the female gomphids. 



An editorial in Nature, volume 26, 1882, page 89, related a curious fact observed 

 by Signor Stefanelli in regard to a dragonfly {yEschm cyanea) often met with near 

 Florence. There were several nymphs of this species in a cistern of water. Some 

 which were almost ready for transformation came out of the water a little way during 

 the night, and attacked several teneral imagos which could not yet fly and voraciously 

 devoured them. It was suggested that this singular practice m.ay explain why one 

 finds such a small number of ^schna cyanea in comparison v\dth the number of nymphs. 

 But this is more easily explained by the migration of the tenerals already described 

 (p. 188), and we must regard such a practice as this as extremely exceptional rather than 

 as an ordinary occurrence. 



4. Ants, Spiders, Robber FuES, and Frogs. — These also eat teneral dragonfiies, 

 and the spiders capture fully matured adults. Two tenerals of L. liicttwsa were eaten 

 alive by a colony of black ants on the banks of pond 4. The ants seized them on all 

 sides with their mandibles and tore them in pieces, dragging off the fragments to their 

 nest. 



The webs of the common black and yellow spider, Argiope, are thickly scattered 

 through the vegetation along the shores of the ponds, and from them the author secured 

 many specimens of Ischnura verticalis, Enallagma civile, E. hageni, Argia putrida, and 

 tenerals of Sympetrum ruhicundulum, L. luctuosa, and Brythemis simplicicollis. Wil- 

 liamson (1899, p. 236) has recorded a similar experience in Indiana. A large water 

 spider, common around the shores of the ponds, also catches teneral dragonfiies on the 

 grass stems at the edge of the water. 



Williamson (1899, p. 235) noted a large robber fly carrying a teneral Sympetrum 

 ruhicundulum, which it had doubtless killed, and Dyche (1914, pp. 151 to 153) found 

 dragonfiies in the stomachs of several large bullfrogs. 



The little cricket frog, Acris gryllus, is also a confirmed eater of damselfiy imagos. 

 His usual roosting place is upon the floating algae at the surface of the water, where he 

 watches for the damselflies when they come to deposit their eggs. When caught, the 

 damselfiy is much longer than the frog's body, but the latter swallows it slowly and keeps 

 swallowing until it has entirely disappeared. 



5. Parasitic Mites and FuES. — ^Tillyard (191 7, p. 331) made the following 

 statement : 



Dragonfiies whose larvae live in still water are frequently found covered with the young of a species 

 of small red mites (family Hydrachntdse). The adult probably attacks the dragonfly at metamorphosis, 

 placing either its eggs or viviparous young on the under side of the thorax, the bases of the wings and legs, 

 or the abdomen, to which they are afterwards found clinging. In this way the dragonfly is used as a 

 means of dispersal by the Arachnid, and the young mites are carried from one pond to anotlier, where 

 some of them drop off. 



