LEAVES FROM MY NOTE-BOOK. 141 



formidable. In moving about there is always the danger of being 

 accidentally dislodged ; and if a larva should let go or miss its 

 hold in a rapid stream, what is likely to happen ? It seems inevit- 

 able that it would be swept away, and who knows where it would 

 come to rest ? Yet, as it will shortly be seen, the SiniuliutJi is 

 quite safe. 



"The little rivulet," says Mr. Miall, "which I am accustomed 

 to visit for the purpose of observing this larva is a bright, clear 

 stream, flowing over watercress and brook-lime, and forget-me-not. 

 A few feet lower down it ends in the wide and stony Wharfe, a 

 stream of quite different character, in which I have never been able 

 to discover a single specimen of this species. Other brooks in 

 which the larvae are plentiful empty themselves into rivers unsuited 

 to an insect of habits so peculiar — muddy, sluggish, or brackish. 

 But this difficulty has been provided against, and I find that the 

 larva is seldom or never swept away, even when its haunts are 

 invaded by a groping naturalist. ... If seriously alarmed, 

 the larva lets go, and immediately disappears from sight. But by 

 watching the place attentively we should, before long, see the larva 

 making its way back, and in a minute or two it will be found 

 attached to the same leaf from which it started, or to some other 

 leaf equally convenient. 



" On close observation a thread, or perhaps a number of 

 threads, become visible in the white ground. (Mr. Miall, for pur- 

 poses of observation, had pushed a white plate in amongst the 

 leaves, when the dark-coloured larva became perfectly evident.) 

 These threads are, in general, stuck all over with small vegetable 

 particles, Hke fine dust. The threads extend in all directions from 

 leaf to leaf, and the larva has access to a perfect labyrinth, along 

 which it can travel to a fresh place by help of the current, and 

 with the speed of lightning. I suppose that it grasps the threads 

 with its pro-thoracic claws, for when it comes to rest it is always 

 found holding on by them. . . . Although the larva commonly 

 slides along a thread previously made, and easily seen to be an 

 old one by the small particles that cling to it, it can, upon a sudden 

 emergency, spin a new thread, like a Spider or a Geometer larva. 

 The new threads are perfectly clear and clean ; they are therefore 

 invisible on a white ground so long as the larva is submergedy^ ^^IC/^ / 



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