INSECTS AND PLANTS IN MID-WINTER 3 



INSECTS AND PLANTS IN MID-WINTER. 



Yesterday I walked to Barden Tower to find some 

 Simulium larvae These little black creatures, from 

 one-eighth to half an inch long, cluster on leaves of 

 water-cress and brooklime in a clear and rapid stream, 

 which flows down from the moors to the Wharfe. 

 The manoeuvres of this larva have been a favourite 

 study of mine. I have watched it clinging to smooth 



FIG. i, Group of larva; of Simulium attached to a Atone. 



leaves or stones, in spite of the full force of a moun- 

 tain current. It keeps its hold by means of a sucker 

 armed with a circle of hooks at the tail-end of its 

 body, or by a somewhat similar sucker just behind 

 the head. If compelled to let go by threatening 

 danger, it disappears from view in a moment, but the 

 attentive observer can by and by see it wavering in 

 the clear torrent, and then slowly travelling back, not 

 by swimming, but by hauling itself in along a thread, 



B 2 



