38 
THE YORKSHIRE NATURALISTS’ UNION’S 
SEVENTIETH ANNUAL REPORT 
FOR 1932 
[Continued from page 24) . 
ENTOMOLOGICAL SECTION [continued). 
An interesting collection of material is at present being worked upon 
from just outside the Yorkshire boundary collected by Mr. Pentelow, 
and it contains such good species as Rhithrogena fraglyi, which is a species 
not yet recorded in Yorkshire. 
Some of the results of the investigations into the Yorkshire Mayfly 
fauna during 1931 made by Mr. Hincks and myself, appeared in The 
Naturalist for February, 1932, and included three additions to the 
Yorkshire list, but much of the information which we obtained could 
not be placed in a short paper of this description. 
A large number of records from a wide range of Yorkshire localities 
have been obtained this year together with some biological observations, 
which may prove of interest, and we hope to be in a position to put 
these on record. 
Mr. Hincks took a female Rhithrogena at West Tanfield last year, 
which, we believe, will prove to be an addition to the British List. 
Unfortunately, this cannot be determined for certainty without further 
materials, but it appears to be amply distinct from R. fraglyi and R. 
semicolorata. 
At Ryhill, on the Entomological Section’s field meeting in June, 
the cast pellicles of Caenis macrura were noticed upon trees near the 
water and there followed a search for the nymphs which were found in 
numbers beneath algal growth at the edge of the reservoir. These 
nymphs were difficult to see owing to their resemblance in colour to the 
reservoir bed. 
No additions have as yet been made to the Yorkshire list during 1932. 
Our knowledge of Mayfly nymphs and their determination is ex- 
ceedingly poor, and a good deal of time has been spent in collecting 
and observing Yorkshire specimens in the nymphal state. The following 
three species : Caenis macrura, Cloeon dipterum and Ecydonurus venosus 
have each been captured as fairly well developed nymphs and successfully 
kept until emergence of the adult. Other species have been taken in the 
nymphal state, but have succumbed in our aquaria either through in- 
adequacy of the aeriation of the water or of their food supply. 
Mr. W. Withell has done some good work by supplying some excellent 
photographs of wing slides. 
I have received good material from Mr. W. Doughty and Mr. A. G. 
Davies, who are keen Yorkshire fly fishermen. 
A list of records for 1932 is appended, together with a reference to 
those who have contributed to form it. Attention is drawn to the 
probable increase in this list when the remaining material which has been 
sent in is worked out. 
NOTE. — At the Annual Meeting to-day, Mr. J. Wood has handed 
in a very excellent collection of material to be worked up, which will 
increase the list of records in due course.- — r 5/1 0/32. 
List of Records for 1932. 
Ephemera danica Mull. ... Harewood Bridge, 13.6. A few speci- 
mens only seen, and one male and one 
female captured. 
Meanwood Beck, Leeds, 16.6. Seen in 
thousands swarming both sexes, flying 
from the beck in evening up road. 
(W. W.) 20 specimens sent to me. 
The Naturalist 
