515 MOTIONS OF INSECTS. 



when they are flying or swimming. — •! was once muph dit^erted by observ- 

 ing the actions of a minute moth upon a leaf on which it was stationed. 

 Making its i)ead the centre of its revolutions, it turned round and round 

 with considerable rapidity, as if it had the vertigo, for some time.^ I did 

 not, however, succeed in my attempts to take it. — Scaliger noticed a simi- 

 lar motion in the book-crab (^Chelifer cancroides).^ 



Reaumur describes in a very interesting and lively way the gyrations of 

 the Ephemerae, before noticed, round a lighted flambeau. It is singular, 

 says he, that moths which fly only in the niglit, and shun the day, should 

 be precisely those that come to seek the light in our apartments. It is 

 still more extraordinary that these Ephemerae — which appearing after 

 sunset, and dying before sunrise, are destined never to behold the light 

 of that orb — should have so strong an inclination for any luminous object. 

 To hold a flambeau when they appeared was no very pleasant office ; for 

 he who filled it, in a few seconds had his dress covered with the insects, 

 which rushed from all quarters to him. The light of the flambeau 

 exhibited a spectacle which enchanted every one that beheld it. All 

 that were present, even the most ignorant and stupid of his domestics, 

 were never satisfied with looking at it. Never had any armillary sphere 

 so many zones, as there were here circles, which had the light for their 

 centre. There was an infinity of them — crossing each other in all direc- 

 tions, and of every imaginable inclination — all of which were more or 

 less eccentric. Each zone was composed of an unbroken string of 

 Ephemera?, resembling a piece of silver lace formed into a circle deeply 

 notched, and consisting of equal triangles placed end to end (so that one of 

 the angles of that which followed touched the middle of the base of that 

 which preceded), and moving with astonishing rapidity. The wings of 

 the flies, which was all of them that could then be distinguished, formed 

 this appearance. Each of these creatures, after having described one 

 or two orbits, fell upon the earth or into the water, but not in consequence 

 of being burned.'' Reaumur was one of the most accurate of observers ; 

 and yet I suspect that the appearance he describes was a visual deception, 

 and for the following reason. I was once walking in the day-time with 

 a friend'', when our attention was caught by myriads of small flies, which 

 were dancing under every tree ; — viewed in a certain light they appeared 

 a concatenated series of insects (as Reaumur has here described his 

 Ephemera?) moving in a spiral direction upwards ; — but each series, upon 

 close examination, we found was produced by the astonishingly 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- 

 Ichneuman. 



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

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

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



' Mr. Wcstwood informs us that he has repeatedly observed the same proceeding and that 

 the insect is Simaethis fabriciana. 

 « Lesser, 1. i. 2 18. note 22. a Reaum. vi. 48 J. t. xlv. f. 7. 



* The persons observing the appearance here related were the authors of this work. 

 ' Lack. Lapp. i. IQ-l. 



