284 



Knab (F.). a New American Plilehotainus. — Jnsecutor Inscitine 



Mensfruiis, Washington, \, no. 11, Nov. 1913, pp. 135-137, 



1 fig. ■ 



A new species of PldchotoDuif^, wliit-li occurs in iissociation witli 



man, is described, viz. P. atroclavafiia. It was taken on Gasparee 



Island, Trinidad, in Augnst 1913, by Mr. F. W. Uricli. 



Massonxat (E.) & ViiVET (C). Ethologie et pupation chez les 

 Dipteres pupipares et les Oestrides. [Ethology and pupation 

 in pupiparous Diptera and in Oestrids.] — C.R. Hebdom. Soc. 

 lie Biol., Fans, Ixxv, no. 26, 18th July 1913, pp. 49-51. 



The authors say that in the conrse of their studies of pupipar- 

 ous Diptera and of Oestrids they have endeavoured to breed the 

 insects from larvae. Their attempts were not always successful 

 and sometimes were attended with great difficulty. The larvae 

 of Melophafius orinns, L., and Hippobosca equina, L., extruded 

 before maturity remained white and never produced adults. This 

 premature birth of an immature larva may be pro^-oked artificially 

 by slightly pressing the abdomen of the female when gestation 

 is^ well advanced. Properly developed larvae turn brown in two 

 or three hours. Similar observations were made on Hypoderyua 

 bovis, de Geer, and the authors' observations lead them to the 

 conclusion that in order that the larva of Hypodeima nniy 

 develop, it must remain in its host until the moment before pupa- 

 tion. This is not the case with the larvae of two other Oestrids, 

 Gastrophilus equi, E., and Oestrus ovis, L. In June and July 

 a large number of larvae detached either from tlie stomach of a 

 horse or the nasal fossae of a sheep may remain from one to 

 three days on non-nutritive media and still mature properly. 

 The authors say that this capacity for maturation away from the 

 host results from the fact that the parasitism of these insects is not 

 so accentuated as that of Hypoderma bocis. In the last larval 

 stage of Hypoderma the movements are extremely restricted. 

 On arriving at maturity the larva enlarges the opening in the 

 skin and falls to the ground; it turns black almost immediately, 

 and about 2 hours afterwards is transformed into a rigid pupa. 



The larva of G. equi, if placed upon friable soil, partly buries 

 itself. It is more mobile than the larva of Hypoderma, but 

 much less active than that of Oestrus ovis, wliich is quite capable 

 of escaping from a glass vessel. 



The duration of pupation is determined by the temperature. 

 In //. equina it varies from 28 to 35 days at a temperature of 20° 

 to 21° C. (68°-9° E.); but if kept at 35° C. (95° E.) the period 

 was onlv 25 days, whilst a pupa, in August, on Mount Pilatus 

 at 700 metres above sea-level, required 50 days for the emergence 

 of the insect. Oestrus ovis required 2T to 29 days at a constant 

 temperature of 35° C. (95° E.). 



Hypoderma bovis during the whole of its larval period is 

 exposed to exceedingly constant conditions of temperature and 

 abundant nutrition, yet shows very great individual variations. 

 Pupae from the same host placed in identical conditions showed 

 a difference of 6 days in the time required for development. 



