ON THE OCCURRENCE OF CEPHENOMYIA RUFIBARBIS 157 



clothed with hairs, these forming a tawny transverse band 

 before the suture, continuous in colour with the pubescence 

 on the hinder part of the head ; hinder part of thorax clothed 

 with black hairs. Scutellum with tawny hairs. Sides of 

 thorax with light tawny hairs ; beneath the base of the wings 

 a patch of almost white hairs. Abdomen densely clothed 

 with hairs, which on the first two segments are dirty yellow, 

 on the third and fourth black, and from the hind border of 

 the fourth segment to the apex white. Under side of 

 abdomen with long, white, silky hairs ; at the base on each 

 side a patch of white. Wings grayish, the veins blackish 

 brown, sometimes clouded with brown. Alula; dirty white, 

 edged with brown. Halteres dark brown, with white tips. 

 Legs black, femora with gray and black hairs, tarsi reddish 

 brown with the apices of the joints darker. 



The life-history of this fly is quite as interesting as that 

 of its allies. The females are viviparous, and the larvae are 

 parasitic upon the Red Deer (Cervus elaphus, Linn.). From 

 May to July the adult females are to be seen flying slowly 

 and noiselessly in vertical circles round and round the heads 

 of their victims, who become greatly disturbed and begin to 

 snort and kick. Suddenly a fly darts down upon the open 

 nostril of the restless animal, soon flying up again, only to re- 

 peat this irritating process several times. The poor victim 

 becomes still more excited, and tries to scratch its nose with its 

 hind feet, or endeavours to rub this organ, which is sometimes 

 already bleeding, upon its fore feet, all the while sneezing 

 violently, and occasionally by this means succeeding in dash- 

 ing its little enemy down to the ground. In the meantime 

 the fly has succeeded in injecting into the nostril a drop of 

 fluid containing minute, living, and very active maggots. 

 These adhere firmly by means of the hooks with which they 

 are provided, and by constant wriggling work themselves 

 continually onwards until they come to lie at the back of 

 the throat, where they remain until almost ready to enter 

 the pupal stage. They are then forcibly ejected from the 

 throat by the coughing and sneezing of their host. When 

 fully-developed the larvae measure from twelve to thirteen lines 

 in length. Their colour is dirty yellow, the upper border of 

 the last segment of the body yellowish brown, the end of the 



