THE CANADLA.N ENTOMOLOGIST. 39 



CORRKSFONDENCE. 



DU'IKKUUS KNKMIES OF IHK PHVI.I.OXKRA \ASTATR1X. 



I'o the Eiiitor : A\'ill you permit me to refer briefly to the Re\'. 'i\ VV. 

 Eyles's descrijition of Diplosis ^rassator. on p. 238, vol. xiv. 1 am 

 credited witli the reference of the insect to the genus Diplosis. though in 

 reahty I have never seen Mr. Fyles"s insect, whether in the larva, pupa or 

 imago state. I simply e.xpressed the opinion at Montreal, both to your- 

 self. Mr. Editor, and to Mr. Fyles, that the insect would prove to be a 

 Dip/osis, from the general account of the larva then and there given to 

 me. It is rather unjust to quote another's mere opinion given in this 

 manner, when, b)' submitting specimens for examination, a definite and 

 more authoritative decision could have been obtained.* In this case the 

 reference seems to be correct, a fact which, under the circumstances, is a 

 mere accident. 



I need hardly say that there is nothing in the description that is not of 

 so general a nature as to be at most generic, so that we have no evidence 

 whatever as to whether the species is new or by what characters it is to be 

 distinguished from the hitherto described species of the genus. 



Hut my object in writing is to point out the fact that there are two 

 different orange-colored Dipterous larVcC that attack the gall-inhabiting 

 form of Phylloxera vastatrix in all its stages of growth, and particularly 

 in the egg state. Neither of them is parasitic, strictly speaking, but 

 merely predaceous, not only on Phylloxera vastatrix, but on other gall- 

 making Phylloxerians and Pemphigians. First, we have the pale-orange 

 or .salmon-colored Diplosis larva referred to by Mr. Fyles, with the usual 

 breast-bone of the Cecidomyids, and with the pupa showing the antennal 

 processes at the anterior end. Second, a deejjer orange larva contracting 

 to a brown pupa with two oblique processes from the anal end, and pro- 

 ducing a fly of a totally different family (Agromyzidae) belonging to the 

 genus Leucopis. This is by far the most efficient of the two enemies, and 

 the larvjfi have undoubtedly been at times confounded, as witness the dif- 

 ferences between Walsh and Shimer (Practical E?itomologist, ii., p. 19). 

 'J'he Leucopis, so far as I have investigated the matter, is undescribed and 

 is referred tf» in my manuscript notes as Z. phylloxerce. 

 C. V. RiLEV, Washington, D. C. 



* The Editor is solely responsible for this reference to Prof. Riley ; Mr. Fyles knew nothing of it 

 until he saw it in print. The opinion given in Montreal as to the generic position of this insect was so 

 unhesitating and positive in its character that we thought it not offly safe but due to Prof. Kiley to credit 

 him with the determination. 



