NOTES ON THE MYIASIS-PRODUCING DIPTEKA. 261 



for it is usually then that they leave them. The camel bot larvae always leave their 

 hosts in the evening, when the camels are feeding. They will be found buried in the 

 earth and under leaves, etc. 



In the case of recently killed wild animals, such as deer, antelopes, pig, wart-hogs, 

 rhinoceroses, zebras, elephants, etc., if the observer has time, many larvae may be 

 collected from the nose, accessory sinuses, throat, nasopharynx, skin, stomach and 

 duodenum. The largest and the smallest larvae should be specially selected, for 

 in this way the nearly mature third-stage larvae, and sometimes the second stage, 

 will be obtained. The larvae should be placed in tubes until they can be preserved 

 by killing them in boiling water or alcohol. I hope those who have opportunities 

 while on shikar trips in Africa and India will collect any Oestrid larvae they may 

 lind and preserve them as described above and send them to Dr. Marshall. The hosts 

 of many of these flies are gradually being exterminated, and with them these inter- 

 esting insects will disappear before we have time to learn all there is to l^e learnt from 

 their larvae. 



The first-stage larvae of all oviparous Oestrid ae can be obtained by collecting 

 the eggs from the hairs, skins, tusks, trunk, etc., of their respective hosts, whether 

 dead or alive. The hairs, or the piece of skin, should be cut off and placed in a dry 

 tube with a well-fitting cork, and watched every day. In a few species the larvae 

 hatch out of their own accord, such as those of Gasterophikis veterinus [nasalis], 

 Hypoderma bovis and H. lineata ; others again only require moisture, when they at 

 once escape from the eggs, as in the case of the larvae of Cohboldia elephantis ; 

 and others again require friction as well as moisture, such as the larvae of Gastero- 

 philiis intestinalis. Recently Captain Cross, C.V.D., sent me a large number of 

 horses' hairs with eggs of Caster ophilus intestinalis var. bengalensis from the legs of 

 horses in the Punjab. The larvae could not hatch out when the eggs were only 

 moistened ; but as soon as they were compressed, the opercula broke away. .. This 

 friction is applied by the tongue of the horse. 



All such first-stage larvae should be dropped into hot 70 per cent, alcohol and 

 placed in a small tube with a good cork, which must be paraffined in order to prevent 

 the alcohol escaping. 



In the case of the larviparous Oestkidae, such as the Oestrinae, the first-stage 

 larvae can only be obtained by catching a female, either when depositing its larvae 

 at the entrance to the nose, or in the neighbourhood of its host, on the off chance 

 that it may contain larvae ready to be extruded. The flies should be preserved in 

 70 per cent, alcohol, for the larvae can always be dissected out afterwards ; and the 

 fly can be identified from such spirit specimens. This also applies to species of Wohl- 

 fahrfia and Sarcopliaga, for these flies are larviparous in habit. 



In concluding these notes, I would like to take this opportunity of thanking all 

 those who have given me material bearing on this subject. Owing to the long 

 distance it will of course be impossible to send me living larvae, so that the breeding 

 out of the flies will, in the first instance have to be carried out on the spot. But as 

 more material other than Indian becomes available, it will be possible to give a 

 complete description with a key to the larvae of the myiasis-producing Diptera, so 

 that a Medical or Veterinary Officer when he comes across a case may be in a position 

 to determine the species without having to breed out the fly ; breeding experiments 

 are always difficult, take up a lot of time, and, as often as not, fail. Medical and 

 Veterinary Officers have unique opportunities of collecting the larvae of these flies 

 and of studying their habits, but I believe many are deterred from doing so because 

 there is no easily accessible account of these interesting parasites of man and animals ; 

 I trust these notes will in some way fill this hiatus. And lastly, I would like to point 

 out that comparative studies of the first, second, and third-stage larvae of these 

 higher Diptera cannot but lead to a better knowledge of the relationships of the adults. 



