MOTIONS OF INSECTS. .373 



vise, beating the air rapidly with their wings, till they 

 have ascended five or six feet above the tree ; then they 

 descend to it with their wings extended and motion- 

 less, sailing like hawks, and having their three tails 

 elevated, and the lateral ones so separated as to form 

 nearly a right angle with the central one. These tails 

 seem given them to balance their bodies v/hen they de- 

 scend, which they do in a horizontal position. This 

 motion continues two or three hours without ceasing, 

 and commences in fine clear weather about an hour be- 

 fore sun-set, lasting till the copious falling of the dew 

 compels them to retire to their nocturnal station^. 

 Our most common species, which 1 have usually taken 

 for the E. vulgafn, varies from that of De Geer in its 

 proceedings. I found them at the end of May dancing 

 over the meadows, not over the trees, at a much earlier 

 hour — at half-past three — rising in the way just de- 

 scribed, about a foot, and then descending, at the di- 

 stance of about four or five feet from the ground. An- 

 other species, common here, rises seven or eight feet. 

 I have also seen Ephemerae flying over the water in a 

 horizontal direction. The females are sometimes in 

 the air, when the males seize them, and they fly paired. 

 These insects seem to use their fore legs to break the 

 air; they are applied together before the head, and 

 look like antennae. — Empis maura, a little beaked fly, 

 I have observed rushing in infinite numbers like a 

 shower of rain driven by the wind, as before observed'', 

 over waters, and then returning back. 



It is remarkable that the smaller Tipulidce will fly 

 unwetted in a heavy shower of rain, as I have oflen 



' De Gecr, ii, G3S— . * See above, p. 7. 



