the Egg-laying of Trichiosonia. 175 



nearly but not quite fully expanded and had very delicate 

 tissues, younger leaves were several times accepted but 

 never older ones. 



Poplars margined the wayside where I found the insects, 

 and as the quality of its leaves is very similar to that of 

 the Salices affected, I think it not improbable that the poplar 

 is also patronised. 



The subject of this paper is the action of the saws, so that the 

 precise determination of the species of Trichiosoma observed 

 is of less importance. This is fortunate, as Mr. Morice does 

 not find it easy to say which species is in question ; for my 

 purpose it will be enough to report that he says, " I should 

 feel quite certain that it was betuleti, KL, if only you had 

 not found it on Salix — " " — betuleti has always been 

 believed to be exclusively attached to Betula and — mainly 

 on that account — has long been reckoned as a variety of 

 the well-known and universally distributed T. lucorum,, 

 w^hich abounds wherever Betula is plentiful. The only 

 two species recorded as attached to Salix are latreillii 

 and sylvatica ; yours, I am satisfied, can be neither of these, 

 unless all Trichiosomas are forms of a single species." 

 He adds that the species is almost certainly the betuleti 

 of Costa, which is placed by Cameron under lucorum, 

 and is not the species given as betuleti, KL, by Cameron 

 (" British Phytoph. Hymenoptera," Ray Soc. Vol. Ill, 

 pp. 22-24). 



I have various notes made at the time, some of which 

 I may quote. I also made some rough diagrams of the 

 progress of the operation of cutting the pockets, etc. 

 These I elaborate a little, but they still remain only dia- 

 grams ; I am no draughtsman, but if I were, the operation, 

 though slow enough for observation, is much too rapid for 

 any careful drawing. 



On April 26, 1 note that I saw " 5 eggs laid on the smooth 

 narrows-leaved willow. The sawfly crawled about in a 

 haphazard sort of way, nmch as when moving with no 

 obvious object. Almost unexpectedly, however, she would 

 come to a spot with the end of the abdomen against the 

 margin of the leaf, and there resting, a rhythmical movement 

 of the end of the abdomen took place ; at first this seems to 

 be a process of the two larger front eminences endeavour- 

 ing to get a hold of the margin of the leaf or some sort of 

 fixity in regard to it, so that the saws could properly begin 

 to operate." 



