278 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



chiefly aphides, entangled in most of them. This flight of gossamer ap- 

 pears to have been quite general throughout Great Britain, as it was no- 

 ticed in England, Wales, and even in Ireland.' 



Mr. Black wall is undoubtedly correct in the suggestion which he makes 

 as to the origin of gossamer showers. My own observations, at least, are 



precisely in the direction of his conclusion. As has already been 

 rig-m o ^.^j ]^ jj^^ aerial excursions of spiders in the United States usually 



occur in the soft, balmy days of early autumn, during the months 

 of September and October, although they occur in a less degree during the 

 first warm days of June. The reasons for this are manifest. In the first 

 place the conditions of the atmosphere are favorable. The balmy weather 

 invites the spiders to issue from their hiding places and attempt aerial 

 flight. The wind is not high enough to disturb their excursions, and yet 

 the temperature is sufficiently high to cause ascending currents of air. 

 Were the weather cold or rainy spiders would not venture forth. Were 

 the wind high its violence would greatly interfere with their excursions. 

 Were the air perfectly still it would be impossible for them to mount 

 above the earth. But the conditions being favorable, as they generally are 

 in the halcyon days of our American autumn, immense numbers of sjii- 

 ders, but particularly the young, may be found upon all manner of elevat- 

 ed objects — blades of grass, weeds, bushes, fences, and what not — essaying 

 an aeronautic flight. 



In many, and I would venture to say in the great majority of cases, 

 before a successful ascent is accomplished many unsuccessful attempts are 



made. A spider will assume the proper position and spin out 

 J"^^ a long thread. For various reasons, which we are not able to 



explain, it fails to mount aloft. The thread floats in the air 

 until it is whipped off by the breeze. One, two, or a dozen attempts of 

 this sort produce as many floating filaments. These while waving to and 

 fro in the eddying air are sometimes tangled togetlier before they are loos- 

 ened. Others, again, are united in the air after release. If now we think 

 of the unnumbered myriads of young spiders who are abroad at this sea- 

 son, all moved by the common impulse to fly away from their present 

 site, and all making the unsuccessful efforts described, we can imagine 

 the enormous quantity of loose filaments of gossamer threads which would 

 thus be set afloat within a short period of time. 



These, no doubt, ascend to a certain height, at which they become 

 more or less united into a loose, flocculent mass, and from which, in the 

 cool of the evening, or on the cessation of the air currents, they slowly 

 descend, and add to the quantity already fluttering from all points of 

 the herbage on the surface. 



' " Researches in Zoology," by John Blackwall, F. L. S., second edition, London, 1873, 



page 258, sq. 



