482 MOTIONS OF INSECTS. 



they appeared a concatenated series of insects (as Reaumur has here de- 

 scribed his Ephemerae) moving in a spiral direction upwards ; but each 

 series, upon close examination, we found was produced by the astonish- 

 ingly rapid movement of a single fly. Indeed, when we consider the space 

 that a fly will pass through in a second, it is not wonderful that the eye 

 should be unable to trace its gradual progress, or that it should appear 

 present in the whole space at the same instant. The fly we saw was a 

 small male Ichneumon. 



Other circular motions of sportive insects take place in the waters. 

 Linne, in his Lapland tour, noticed a black Tipula which ran over the 

 water, and turned round like a whirlwig, or Gyrinus. 1 This last insect I 

 have often mentioned ; it seems the merriest and most agile of all the 

 inhabitants of the waves. Wonderful is the velocity with which they turn 

 round and round, as it were pursuing each other in incessant circles, 

 sometimes moving in oblique, and indeed in every other direction. Now 

 and then they repose on the surface, as if fatigued with their dances, and 

 desirous of enjoying the full effect of the sun-beam : if you approach they 

 are instantaneously in motion again. Attempt to entrap them with your 

 net, and they are under the water and dispersed in a moment. When the 

 danger ceases they reappear, and resume their vagaries. Covered with 

 lucid armour, when the sun shines they look like little dancing masses of 

 silver or brilliant pearls. 2 



But the motions of this kind to which I particularly wish to call your 

 attention are the choral dances of males in the air ; for the dancing sex 

 amongst insects is the masculine, the ladies generally keeping themselves 

 quiet at home. These dances occur at all seasons of the year, both in 

 winter and summer, though in the former season they are confined to the 

 hardy Tipularia3. In the morning before twelve, the Hoplice, root-beetles 

 before mentioned, have their dances in the air, and the solstitial and com- 

 mon cockchafer appear in the evening the former generally coming 

 forth at the summer solstice and fill the air over the trees and hedges 

 with their myriads and their hum. Other dancing insects resemble moving 

 columns each individual rising and falling in a vertical line a certain 

 space, and which will follow the passing traveller often intent upon 

 other business, and all unconscious of his aerial companions for a con- 

 siderable distance. 



Towards sunset the common Ephemerae (E. vulgatd), distinguished by 

 their spotted wings and three long tails (caudulte), commence their dances 

 in the meadows near the rivers. They assemble in troops, consisting some- 

 times of several hundreds, and keep rising and falling continually, usually 

 over some high tree. They rise beating the air rapidly with their wings, 

 till they have ascended five or six feet above the tree ; when they descend 

 to it with their wings extended and motionless, 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 



1 Lack. Lapp. i. 194. 



2 Compare Oliv. Entomol. in. Gyrinus 4. One species, however, Gyrinus (OrecA- 

 tocheilus) villosus, which, as before observed, pursues its dances only at night, differs 

 also from its congeners in not having the same habit of diving, or at least not in the 

 daytime, when if forced into the water from its hiding-places under stones, all 

 its efforts are confined to endeavouring to regain the shore. {Ann. Soc. Ent. de 

 France, iv. bull. Ixxx.) 



