333 
OLIGOTROPHUS VENTRICOLUS, RUBS. 
A NEW YORKSHIRE GALL-MIDGE. 
PERCY H. GRIMSHAW, F.R.S.E., F.E.S. 
During an investigation of the purple heath grass ( Molinia 
■ccerulea) on the Slaithwaite moors near Huddersfield, the 
Rev. T. A. Jefferies noticed the common occurrence of 
gall-like swellings on the leaf bases of this grass, and on exam- 
ining the swellings he found each to contain several small 
larvae. These were submitted to Mr. E. G. Bayford who, 
however, was unfamiliar with the species. In the hopes of 
breeding out the fly specimens were kept under observation 
in the Biological Laboratory at Huddersfield, and others by 
Mr. Bayford from material sent him from the same locality ; 
both were successful and specimens were .then submitted to me 
for identification on the 13th of June last. 
I was at once suspicious that the insect might prove to be 
the interesting Gall-Midge known as Oligotrophns ventricolus 
Rubs., which was added to the British list of diptera only two 
years ago by Mr. F. W. Edwards (5) from specimens obtained at 
Oldham in Lancashire. Upon the receipt of more material a 
few days later, I was enabled to confirm my suspicions, and 
now have pleasure in submitting a number of details regarding 
the insect which may be of interest to future workers. Al- 
though the discovery constitutes a new county record, yet 
the distance between Oldham and the Slaithwaite Moors, as 
the crow flies, is only a matter of about 10 miles. Since the 
grass is, I believe, a fairly common one, it would be interesting 
to ascertain to what extent it is infested with this gall in the 
area surrounding these two towns, and also whether the insect 
occurs beyond this area.* Mr. Jefferies is, I understand, 
preparing an account of the grass and the malformations, so 
that in the present article I shall confine myself strictly to 
the fly itself in its various stages. 
Oligotrophus ventricolus as a perfect insect was first named 
and described by Riibsaamen in 1899 (2), although four years 
previously he had recorded and described the larva and gall 
produced by it (1). It was briefly referred to by Kieffer in 
1900 (3), figured by him the same year (4), and lastly described 
by Edwards in 1912 (5). These are all the references to the 
species that I have been able to trace, and as most of them 
are in works not of easy access, I have thought it worth while 
* The galls were found in great abundance in 1913- 14, over a wide 
area of the Pennines, and appear to be common where Molinia occurs. 
Miss C. E. Wetherall, who had seen Mr. Jefferies’ specimens, found the 
galls on plants she examined at Sutton Park, near Birmingham, in August 
this year. — T. W. W. 
1914 Nov. 1. 
