254 Benj. D. Walsh on the Insects inhabiting the Galls 



out, i. e. both in antennae, body and legs. 2nd. The black spot enclosing the 

 ocelli is larger, and is confluent with the eye for its entire length, leaving no 

 orbit between them. 3rd. The venter (dried) is honey yellow on the terminal 

 3 or 4 joints, and in the middle only of one or two more. Basal plates black, as 

 in E. s. gemma. When recent the venter was noted as being "greenish" and the 

 legs as "pale fulvous." 4th. The legs (dried) are honey-yellow immaculate, 

 except the extreme tarsal tips. 5th. Tbe basal J of the stigma is whitish, as in 

 E.s.ovum J. Length % .16— .17 inch ; front wing % .17— .18 inch. 



Two % , 9 unknown. One % came out April 28, the other May 

 12. Differs from E. s. gemma % and E. orbitalis % Nort., by the spot 

 on the vertex being confluent with the eye and by the yellowish ground- 

 color; and from the latter also by the pale venter. The size is also 

 larger than that of E. s. gemma ; but E. s. ovum % varies in size fully 

 ns much. Possibly the $ may differ more remarkably from the 9 of 

 those species. 



Genus ETJUEA. — Inquilin.es or Guest-flies. 



Euura perturbans, n. sp. — 9 Differs from the gall-making E. s. 

 ovum 9, only by the dorsum of the abdomen varying from honey- 

 yellow, including the lateral plates, through obfuscated, to deep black 

 with the lateral plates also black. The % does not differ in any re- 

 spect from E. s. ovum % . Probably if I had bred more E. s. ovum 9 , 

 varieties would have occurred there also with the abdomen obfuscated 

 or black above, just as such varieties occur in my Nematus s. pomum 

 9 , n. sp. There is a similar case of extreme range of colorational va- 

 riation in Acordulecera dorsal is 9 Say, which has been already refer- 

 red to in a note. (Above, p. 239.) By way of testing the apparent 

 identity of the two species, I sent a normal 9 of E. perturbans, 

 and a 9 E. s. ovum to Mr. Norton, along with many Z 9 varie- 

 ties of Nematus s. pomum, each specimen numbered, but none of them 

 named. And although, as I fully expected, from the great variability 

 of the 9 , he made two species of A 7 ", s. pomum 9 , yet he pronounced 

 E. perturbans 9 and E. s. ovum 9 to belong to the same species. I 

 think, under the same circumstances, I should have done the same 

 thing myself. Hence we may see how impossible it often is to define 

 the specific characters of different Nematus and Euura, from the mere 

 comparison of cabinet specimens of their imagos. I believe Mr. Norton 

 has arrived independently at the same conclusion, judging from what 

 he says to me. 



Two % , five 9 . One S bred April 7, from the Cecidomyidous 

 gall S. strobiloides, 0. S. ; one S , two 9 , bred May 7 — 22, from the 

 Cecidomyidous gall S. batatas Walsh; one 9 , bred May 16, from the 

 Cecidomyidous gall S. rhodoides Walsh ; all the above from galls of the 



