26 



and tlie forked joint in the males is relatively shorter. The two species 

 differ also somewhat in venation. With j9ru"rt/«s the costal and sub- 

 costal veins are very broad, very much reducing or almost obliterating 

 the costal cell, which in ehenus is of ample proportions. The third sub- 

 marginal cell is in the former species considerably widened above on 

 the side of the radial nervure, and the third transverso-cubital nervure, 

 which lorms the outer border of this cell, is decidedly curved outward, 

 whereas in the latter species the inner and outer bordering nervures 

 are nearly straight and parallel. The under middle cell of the hind 

 wings, also in 2yrivatus, is only about one-third the length of the upper, 

 while in eheuus this cell is at least one-half the length of the upper 

 cell. 



In the male of ehenus the tibise and tarsi are smoky white, the two 

 posterior pairs being darker; inijrivatus these parts are much lighter, 

 almost pure white, except that the tip of the posterior tibiae is dis- 

 tinctly dusky together with the extremities of all the tarsi. 



Mr. Stockley's letter relating to this insect has already been pub- 

 Hshed, but is here reproduced : 



I have sent you by today's mail a box containing some flies and their eggs on 

 some sweet potato leaves. Last year vras the first time they made their appearance 

 in my potato patch. They came the 1st of July and deposited their eggs on the 

 eaves; when the eggs hatched these worms would eat the leaves to a comb. This 

 continued for about four weeks. The potatoes, wherever the fly was, did not make 

 any yield at all. This year the fly made its appearance at the same time they did 

 last year. Will you please tell me what kind of a fly it is and whether it will do any 

 serious damage? 



The deposition of the eggs in the under side of the leaf by the female 

 fly is shown, natural size, at a. It will be seen that thej^ are placed for 

 the most part in parallel rows bordering the principal veins, the inci- 

 sions of the ovipositor being next to the veins. When iirst deposited 

 the position of the agg is shown by a circular or oval blister, at one 

 side of which is the discolored slit in the epidermis made in inserting 

 the Qgg. As is the case with saw-flies generally the Qgg expands con- 

 siderably before the hatching of the larva — increasing the prominence 

 of the blister-like spot — and on the emergence of the young larva 

 through the slit left by the ovipositor the blister is lengthened and 

 gives the pouch-like or guttiform appearance shown enlarged at 1). 



Xone but young larvae were received, and these, together with the 

 other material, were dried and no opportunity offered to obtain the later 

 stages. 



The larvae closely resemble those of ehenus^ figured in the article 

 cited on that species, both in general appearance and in the disposi- 

 tion of the spines on the body. A newly-hatched larva is shown in 

 outline at c. 



A single cocoon of this saw-fly was received, from which a very hand- 

 some Tachinid parasite was reared. The cocoon is about five- sixteenths 



I 



