Carpenter & Hewitt — Genitalia and Larva of the Warble-fly. 269 



tlie egg or the larva must be swallowed by the cow or calf, and the latter 

 work its way through the gullet and the tissues to its final position beneath 

 the skin of the back ; maggots in the second stage have been repeatedly foiind 

 in the sub-mucous coat of the gullet and elsewhere. For facts and discussions 

 bearing on this question, reference may be made to the recent writings of 

 Imms ('06) and others. 



In the investigations at Ballyhaise the attempt was made, by muzzling 

 and otherwise, to prevent cattle from licking themselves, uuder the belief 

 that they should thus be protected from Warbles, if the parasites really enter 

 by the mouth ; so far it has been found that the practice furuislies, at most, 

 incomplete protection. Experiments on the same lines are being continued, 

 and a further report will shortly, it is hoped, be issued. Last year's work, 

 however, enabled us to obtain a fairly large number of flies, reared from 

 maggots caught by " sleeving " over the holes in the cattle's backs, and we — 

 as well as Glaser in Germany — were fortunate enough to observe the newly 

 hatched maggots of Hypoderma bovis, which had previously been unknown. 

 Material was thus furnished for anatomical study of general entomological 

 interest, the results of which are now published with the Department's 

 approval. The reproductive organs of Hypoderma, except the ovipositors, 

 have never, we believe, been described ; and we are especially glad to be able 

 to make a comparison of the male genital armature iu the two species of 

 Warble-fly, and, further, to compare the condition of the structures as we 

 observe them with what has been described by other students in allied genera 

 of Diptera. It is now recognized that the Warble-flies are nearly related to the 

 group of the House-fly and Blow-fly, whose members have long been favourite 

 subjects for anatomical study. We find that Glaser, in the paper already 

 mentioned, has to some extent anticipated us in his description of the newly 

 hatched maggot — -a wonderfully interesting type of insect larva. Our study, 

 however, serves to supplement, and in some respects to correct, his account. 



The Female Reproductive Organs. 



1. The Ovaries and Oviducts. 



We have studied the internal reproductive organs only in Rijpoderma 

 bovis. The ovaries (Plate XXI, figs. 1, 2) are very remarkable on account 

 of the arrangement of the ovarioles, or ovarian tubes. Each ovary is made up 

 of more than a hundred ovarioles ; in the specimen figured we counted 120 

 in the right ovary and 110 iu the left. From the two or three constrictions 

 visible in an ovariole, we conclude that three or four eggs may be developed 

 in each. A single female would thus produce about 800 eggs ; Glaser ('13) 



2 u2 



