135 



the same species, and lie qiiutes at some Jeuyili the statements 

 of the brothers Sergent (Aun. Inst. Pasteur, 1907, pp. 392-399) 

 to the eit'ect thai in Algeria this Oe.^trtis lays its eggs in the noses, 

 eyes or mouths of human beings in those parts of the country 

 wliere slieep are scarce. But man is not a true host for these 

 insects and the hnvae fail to develop, the inflammation caused 

 by them usually disappearing- in from 3 to 10 days. 



A full description is given of the anatomy of the fly, and it is 

 •contended tliat the rudimentary (diaracter of the proboscis and 

 digestive tract sulficiently indicate that no food is taken by the 

 adult insects, contrary to the opinion of Collinge, who states that 

 they feed on the nectar of flowers (Eept. Injur. Ins., 1904, p. 53). 

 Dr. Portchinsky also finds some difficulty in undeistanding' the 

 statements of Theobald and Collinge to the effect that Oe.sfni's avis 

 sometimes deposits, not larvae, but eggs round the noses of sheep 

 (Jl. Econ. Biol., i, p. 72), as tliis is quite contrary to what is 

 known of the habits of the fly in Russia, nor, in his experience, 

 wduld sheep permit the insect to settle on their Iieads. He can 

 only suggest that these are anomalous cases, due to some diseased 

 condition of the fly. 



The insect is most active during the hot hours of the day, and 

 is very sensitive to a fall in temperature ; in the early morning and 

 evening, and also during wet or windy weather, it hides in holes 

 in walls or similar places. 



A detailed account is gi\-en of the first larval stage, which has 

 not been previously described, for, according to the author, 

 €ollinge's description applies to the third stage only. The first 

 stage closely resembles that of Rhinoestrus j>urpvreus, Br., but 

 no anal papillae are present. AVhen it has penetrated into the 

 frontal sinuses, the cavities of the ethmoid bone, or those of the 

 horn or jaw, the larva loses all its bristles and hooks and becomes 

 transformed into its second stage, which appears to be one of 

 rest ; in this condition it passes the autumn and winter with but 

 little change. During the spring and early summer the larva 

 passes into its third and last stage, which is fully described. It 

 is principally in this stage that the larvae cause in sheep the 

 fits which are known as " false gid." 



The usual number of larvae found in the sinuses is from 1 to 8, 

 but sometimes there are from 20 to 40, and Zurn states that he 

 has even foundGO to 80 larvae. AVhen full-grown, the larva drops 

 from the nostril of the sheep, and after seeking cover pupates in 

 about 24 hours. The pupal stage lasts for 25 to 50 days. 



Tlie author describes the manner in which sheeii try to evade 

 the attacks of Oesfnis, their behavitnir before and after infection, 

 and the pathological symptoms caused by the larvae in their 

 various stages. 



In the soutli of Russia Oestrus (juis first appears in the second 

 lialf of May and continues on the wing until xVugust or even 

 September. In 14 females which the author dissected on the 17th 

 October in southern Russia he found eggs in various stages of 

 development and in some cases even larvae. It is practically 

 certain that tJiese insects would have been killed by cold before 

 reproduction was i^ossible. 



30985 



A 2 



