Notes on the metamorphosis of a dipterous insect of the genus 

 Batrachomyia, (MacLeay) the larva of which is Parasitical 

 upon various species of Australian Frogs, by Gerard Krefft, 

 Esq. 



[Read 3rd August, 1863.] 



In the course of my inquiries into the Batrachian Fauna of 

 Australia, I have frequently captured frogs infested with a number 

 of parasites, seeming to be larvae of dipterous insects ; they 

 are generally found between the skin and flesh, just behind the 

 tympanum, but in cases where from thi^ee to four exist upon 

 a single individual, they reach as far back as the anus ; these 

 larvse may be taken for glands at first sight, but closer examina- 

 tion soon reveals a small opening, and a gentle pressure will 

 quickly exhume the yellow parasite. In all cases where the 

 larva was forcibly ejected, the death of the frog, whether large or 

 small, was caused thereby ; and in fact these creatures generally 

 die after the larvee have worked their way out. 



The perfect insect, a small yellow fly, called by Mr. W. S. 

 MacLeay Batrachomyia, was first reared by Mr. George French 

 Angas ; the typical specimen is now in the Australian Museum, 

 and was obtained from a species of Cystignathus (0. Syd- 

 neyensis, Kr.) the most diminutive of our Frogs ; the speci- 

 men which I reared lived on another small Batrachian (Uperoleia 

 marmorata) and is to all appearance a different species. Having 

 obtained a frog in the beginning of April, when the larva had 

 almost reached its full size, and deposited it in a glass vessel 

 with some moist earth and moss, I found that the parasite 

 left its shelter a few days afterwards, the frog dying as usual 

 in consequence. I observed the yellow larva for more than 24 

 hours traversing the moss, and found it after a lapse of 36 

 hours completely ensconced in a black covering, but without 

 being attached to any object ; whilst in a state of nature 

 the Chrysalis is generally fastened to the under side of some 

 piece of rock in damp localities. Thirty -two days afterwards 

 the perfect insect emerged. 



