Ll/e-Instory of Di\fiyhe\ea ohscnvn, Winnerfz. 577 



pallipes, Meig., (3) Systenus adpropinquans, Loew., (4) S. 

 scholtzii, Loew., (5) Aulacoguster rujitarsis, Meig., (6) Pliaoniu 

 cincia, Ti^ii., and (7) an undetermined Syrphid larvas closely 

 allied to the genus Ceria. This wound was also visited by 

 the predaceous larvfe of two Staphylinidse ^ — one belonging 

 ])robably to the genus Quedius sp. (subfamily Staphylininye), 

 the other being possibly a Thamiaraa sp. (subfamily Aleo- 

 charinse). 



Finally, the whole surface of the decomposed sap of this 

 wound, and especially its solidified portions, was covered by 

 myriads of a mite, Htricia hericia, Kramer (Tyroglyphidie), 

 in all the stages of its development. 



The larvae of Dasyhelea were also common in a simdar 

 wound of a horse-cliestnut tree standing on the grouiul 

 between the School of Agriculture and the Downing College 

 grounds, and Mr. W. F. Edwards has kindly communicated 

 to me the following unpublished records concerning the 

 vaiious breeding-places of this midge : — 



(1) J. E, Collin bred it with Culicoides varius, Winnertz, 

 and Culicoides fascipennis from debris of a chestnut tree 

 (Snailwell, Cambs). 



(2) F. Jenkinson reared them from elm sap (Logic, Elgin 

 and Cambridge). 



(3) F. W. Edwards himself obtained Z>. obscura : (a) with 

 Rhyphus fenestralis from the decaying roots of Angelica 

 (Knebworth, Herts), {b) from l-unniug sap of an oak, (c) with 

 Mycetobia pallipes, Systenus sp., and an undetermined Syrphid 

 from running sap of hornbeam, and, finally, {d) with Rhy- 

 phus feiiestralis and Mycetobia from stagnant water in a bole 

 in an oak tree (Epping Forest). 



To find the early stages of Dasyhelea obscura it is sufficient 

 to collect a small quantity of semifluid exudate filling the 

 wound of an elm tree, to stir it in a petrie-dish with a little 

 tap water, and leave it for an hour or more to settle. 

 Examined under the binocular microscope, the eggs, larvae, 

 and pupae of Dasyhelea are very easily detected on the 

 bottom of the dish. 



II. Eggs and Oviposition. (PI. XIX. fig. 4, and text-fig. 1.) 



The female seems to oviposit only once in her life, and 

 the eggs, about 120 in number, are laid simultaneously 

 upon the solid particles sticking out from the exudate or 

 upon the moistened edges of the wound. 



* The identification of these larvai I owe to llie Idndness of 

 Mr. K. G. Blair of the British Museum. 



Ann. d) Mag. N. Hist. Sci'. 9. Vol. viii. 137 



