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F G H ; at the letter K appears a knob, wherein, upon opening it I 

 found a maggot. 



I alfo obferved many dead maggots lying among the knobs, and 

 upon learching after the caufe of this appearance, I found at length 

 a fmall maggot flicking clofe to one of a larger fize, which 

 fmaller maggot feemed to have no power of moving itfelf from 

 place to place, each extremity of its body, particularly the hind 

 part, terminating in a kind of point. This maggot, with its mfouth, 

 had pierced into, and was fixed on the body of the larger one ; and 

 from this and many other instances which I faw of the like kind, it 

 appeared to me, that this fmall maggot was fupported by preying up- 

 on the larger one ; and hence I confidered that were it not for food 

 drawn from thole or the like kind of maggots, thefe fmaller ones 

 would be dellitute of fubfirtence ; for they are not provided with 

 any limbs or organs by which they can faften themfelves to the 

 leaves of trees. 



But how thefe lafl: mentioned maggots could find their way into 

 the internal parts of the knobs or excrefcences was ftrange, and to 

 me entirely undifcoverablc, otherwife than by conjedlure. I fup- 

 pofe, firft, that the larger maggot was produced from an egg laid by 

 fome fly on the leaf of the Willow, and upon its biting or gnawing 

 the vellels in the leaf, a liquid fubftance ifllied forth, furround- 

 ing the maggot on all fides, and in hardening formed the knob or 

 excrefcence we obfcne on the leaf: fometime afterwards another, 

 and a fmaller fly might place itfelf on the knob, and by means of 

 fome weapon or piercer, bore a hole in the knob and lay therein 

 an egg, from which egg, the fmaller maggot might be produced. 



About the middle of July I repeated my obfervations on thefe 

 maggots, and found many of them almoft arrived to their full growth : 

 and fome aftually changed into aurelias or cryfales* : I alfo found 



* The tranflator has taken the liberty to cxprefs the plural number of the word cryfalis by 

 this termination, inftcad of adding another s to it, witli an apoftrophe between the letters, as 

 is fometimes done. 



