244 MAJOR W. S. PATTON. 



of the food of such larvae is not clearly understood, but from a large number of 

 dissections and examinations of the mid-guts of the larvae of the sheep nose-bot 

 {Oestrus ovis), I was unable to confirm Brauer's suggestion that these Oestrid larvae 

 are blood-suckers. The contents of the mid-guts of larvae recently removed from 

 their hosts clearly suggested that they had fed on serous exudations, most probably 

 resulting from the irritation produced by the minute, but deep, punctures made 

 by their mandibular hooks in the mucous membrane. I had several opportunities 

 of examining the naso-pharynx of dromedaries heavily infested with the larvae of 

 their nose-bot, Cephalopsis titillator, and there was no doubt whatever that the mucous 

 membrane was in a pathological condition, and in life would exude much mucus. 



The entire larval stage of the Oestridae is a long one, and is chiefly passed in 

 the third stage, but the adults, on the other hand, are short-lived. Sufficient food 

 is taken in by the third stage larva, and stored up in the form of fat-body, so that 

 when the adults hatch out, particularly the female, there is ample nourishment 

 for the development of the eggs, and even for the hatching of the first stage larvae 

 in utero. The adults therefore do not feed, and as a result their mouth-parts have 

 atrophied for want of use. There can be very Httle doubt that when such larvae 

 are in large numbers, the host suffers, and may, as I will point out further on, even 

 die as a result of a massed infestation. 



The Oestridae are at present grouped in a number of subfamilies according to 

 the structure of the third stage larva, and that of the adults. A few notes on the 

 species belonging to the various subfamilies may be useful to those who have 

 opportunities of collecting any of these flies, either as larvae or as adults. For 

 much of the information given below I am indebted to the exhaustive works of Rodhain 

 and Bequaert, as well as to those of Gedoelst and Roubaud. 



1. Subfamily Gasterophilinae. 

 All the species of this homogeneous group are myiasis-producers in their larval 

 stages, the larvae living in the stomach, and in one case in the duodenum, of the 

 horse and its allies. These larvae have occasionally been found in the stomachs of 

 certain carnivores which had fed on dead horses, donkeys, etc., but this infestation 

 is only accidental. In Russia some of the species now and then deposit their eggs on 

 the hair of the human face, such as the eyebrows, and the first stage larvae then pene- 

 trate the skin, and cause the so-called " creeping myiasis," the little larva burrowing 

 along under the skin, evidently endeavouring to find its way into the ahmentary 

 tract ; they never, however, reach the stomach, and thus do not become mature. 

 As would be expected, such larvae only belong to those species of Gasterophilus whose 

 larvae normally penetrate the skin of the horse, after hatching out of the eg^. and do 

 not depend on moisture and friction to help them to leave the egg, and enter the mouth. 

 Gasterophilus veterinus {nasalis) and G. haemorrhoidalis are the two species whose 

 larvae usually cause this form of myiasis. Gasterophilus intestinalis, on the other 

 hand, cannot do so, as its larvae can only hatch out of the egg with the aid of friction 

 and moisture. 



The following species of Gasterophilus are known in their larval and adult stages :— 

 Gasterophilus intestinalis, De Geer (cqui, Clark). This is the common horse bot of 

 Europe and North America ; it has also been recorded from many parts of Africa, 

 such as South Africa, the Belgian Congo, Senegal, French Guinea, the Gold Coast, 

 etc. It is also found in Australia and New Zealand. In India and Mesopotamia 

 there is a variety, bcngalensis, Macq., which is very common in the north of India. 

 Another variety, asininus, Br., is recorded from the Anglo-Egyptian Sudan, its larvae 

 being parasitic in the stomach of the donkey. 



Gasterophilus haemorrhoidalis, L.— This is also a European and North American 

 species, and Gedoelst records it from the Belgian Congo. Its larvae are parasitic 

 in the stomach of the horse. 



