MOTIONS OF INSECTS. 337 



becomes of them ? What occasions the spiders to mount 

 into the air, and do the same species form both the ter- 

 restrial and aerial gossamer ? — And what causes the webs 

 at last to fall to the earth ? I fear I cannot to all these 

 queries return a fully satisfactory answer; but I will do 

 the best I can. At first one would conclude from ana- 

 logy, that the object of the gossamer which early in the 

 morning is spread over stubbles and fallows — and some- 

 times so thickly as to make them appear as if covered 

 with a carpet, or rather overflown by a sea, of gauze, 

 presenting, when studded with dew-drops, as I have often 

 witnessed, a most enchanting spectacle — is to entrap the 

 flies and other insects as they rise into the air from their 

 nocturnal station of repose, to take their diurnal flights. 

 But Dr. Strack's observations render this very doubt- 

 ful; for he kept many of the spiders that produce 

 these webs in a large glass upon turf, where they spun 

 as when at liberty, and he could never observe them at- 

 tempt to catch or eat — even when entangled in their 

 webs — the flies and gnats with which he supplied them ; 

 though they greedily sucked water when sprinkled upon 

 the turf, and remained lively for two months without 

 other food ^. As the single threads shot by other spi- 

 ders are usually their bridges, this perhaps may be the 

 object of the webs in question : and thus the animals may 

 be conveyed from furrow to furrow or straw to straw less 

 circuitously, and with less labour, than if they had tra- 

 velled over the ground. As these creatures seem so 

 thirsty, may we not conjecture that the drops of dew, 

 with which they are always as it were strung, are a se- 



" Neiie Schriften der Naturforschenden GesseUschafi zu Halle 1810. 

 V. Heft. 



VOL. II. Z 



