N aturalists’ Field Day at Askham Bog. 
329 
the larger dragonflies on the wing, but of the smaller species the some- 
what local Agrion pulchellum was apparently fairly common amongst the 
universally abundant A. puella, A. cyathigerum and Ischnura elegans. 
The only Chrysopa noticed was C. tenella. 
Arachnida. — Circumstances were not favourable to spider collecting, 
and only incidental specimens came to hand, but, although common 
species, the following have not before been definitely recorded from 
the bog : Clubiona reclusa Cb., Linyphia clathrata Sund., Pirata piraticus 
Clerck., Dictyna arundinacea Linn., both sexes spun up together in heads 
of grass, the classic example of conjugal felicity amongst spiders. An 
Erigoniid spider, apparently not long deceased from the freshness of 
its tissues, had been the victim of some parasitic fungus, whose mycelium 
and conical outgrowths were conspicuous. 
Plant Galls.: — W. P. Winter and the writer were responsible for the 
work done in this branch. Several of the forms previously recorded for 
the localityf were again met with, some of them more plentifully and 
extensively, but they are not now enumerated. The galls of Lipara 
lucens Mgn., found in quantity in the same part of the bog where they 
were originally discovered, proved on investigation to be empty except 
for the pupa case, so that the 'fly itself is still a desideratum. It does 
not, as many agents do, perforate the lignified sides of the growth, 
leaving behind it visible evidence of its exit, but makes its way upwards 
between the loose withered enveloping leaves, the larva just before 
entering the pupa state cutting through the hard apex of its cell (which 
the fly itself is incapable of doing), and affixing itself there, so that 
the imago on emerging finds an unimpeded course to freedom. Al- 
though the insect itself did not materialise, the writer bred out from the 
galls he gathered thirteen examples (both sexes) of an inquiline, *Antho- 
myaa gracilis Fin. (named by C. A. Cheetham), an addition to the 
county list. The above two flies are in themselves a striking testimony 
to the value of plant galls as a scientific field study. F. A. Mason has 
since come across Lipara lucens galls in plenty on Strensall Common. 
Including all agents, recognised or otherwise, 35 different kinds 
not before recorded for the bog were noted, amongst them being : 1, 
Iteomyia major Kieff. on Salix pentandra and Saperda populnea Linn, 
on 5 . cinerea, both new hosts ; 2, Perrisia inclusa Frn., P. praticola 
Kieff, Eriophyes atrichus Nal. on Stellaria glauca ; Eriophyesl spec., 
an erineum on hawthorn leaf, and a Psyllidl spec, on a birch leaf, new 
to Yorkshire. 
Several well marked cases of deformation — the shortening and thick- 
ening of stems or floral axes with the consequent close grouping of leaves 
or inflorescence were noticed as being due to Aphrophora spumaria, an 
acknowledged agent abroad, but not yet in this country. The fungus 
Triphragmium ulmariae Wint., which contorts and swells some parts 
of the leaf of its host has also not yet been admitted to the British Gall 
list. 
Unless otherwise stated the locality is Askham Bog, and species new 
to the county are asterisked . 
CoLEOPTERA. 
Saperda populnea Linn, on Salix caprea and *cinerea. 
Mecinus pyr aster Herbst. on ribwort plantain, one example. 
Hymenoptera. 
Pontania pedunculi Htg. on Salix cinerea, Askham Bog and Chandler’s 
Whin. 
Cryptocampus medullarius Htg. on 5 . pentandra, Miss Grainger. 
The next four on oak. 
Andricus trilineatus Htg., Chandler’s Whin. 
1922 Oct. 1 
f Vide The Naturalist, April, 1922. 
