50 THE ENTOMOLOGIST. 



The imago of Nematus abbreviatus is seldom met. with. 

 It may, of course, have been overlooked as belonging to the 

 inconspicuous mass of sawflies with white, yellow, or reddish 

 knees and anterior tibiae, found nearly everywhere ; but it is 

 also possible that the insect is really scarce, and 1 admit that 

 I am the more inclined to adopt this view when I call to 

 mind the difficulty I had in rearing only one larva out of thirty 

 which I possessed : this difficulty must also plead my excuse 

 should a remark be made on the incompleteness of this life- 

 history. In the beginning of May I found every year some 

 green larvae, resembling that represented on our tenth plate, 

 feeding on the leaves of two pear-trees in my garden. At a 

 very early stage of their existence they are found to have 

 bitten round holes out of the leaves, free both of the midrib 

 and of the margin of the leaf; they also rest in a somewhat 

 curved position on the edge of the hole they have eaten out, 

 so that they are only to be discovered by a sharp eye. 



I have never found larvae smaller than that shown at fig. I, 

 so that in this case also it appears very difficult to discover 

 the first and. very earliest stage of the animal's existence. On 

 the petiole, however, of the leaves on which, or rather in 

 which, such young larvae lived, I almost always found a scar 

 (see fig. 2), which appeared to me to indicate the place in 

 which the egg had been concealed from which the little larva 

 had proceeded. It appears that the larvae move from place 

 to place, — that is to say, they do not confine themselves to 

 merely enlarging the hole in the leaf they at first bit out, for 

 many holes are found, of the size of a silver penny, without 

 inhabitant, and also leaves having two or three holes. When 

 the larva has attained the size shown at fig. 3 it feeds indif- 

 ferently from the margin or other part of the leaf, and, having 

 hitherto always assumed a position with the back incurved, 

 it now places itself as nearly as possible in a right line, so 

 that even sometimes the last two or three segments project 

 without any support. Larvae which I had found on the 8lh 

 of May, of the size represented at fig. 1, had, three weeks 

 later, attained their full size, as shown at fig. 4. 



The green colour of the larva in its early stages is somewhat 

 of a yellow tint, afterwards becoming a grayish green on the 

 back, resembling the colour sometimes observed on willow 

 leaves, the ventral surface and the legs being paler, and of a 



