89 



result of observations, the earliest flies caught having all the appear- 

 ances and characters of newly emerged imagines, and he expressed 

 the opinion that house-flies pass the winter as pupae and in no other 

 way. The authors considered these deductions unsatisfactory because, 

 firstly, the " house-flies " were not definitely identified as Musca 

 domestica, and secondly, the winter of Philadelphia is cold and the 

 conditions are not the same as in England and elsewhere. In order 

 to obtain definite information, the authors published a circular in 

 certain journals asking for specimens to be sent to them from as many 

 dift'erent sources as possible. Between 19th January and 27th April 

 1914, 58 consignments were received from all parts of England, none 

 being sent from Scotland, Ireland or Wales. The specimens sent com- 

 prised : — Pollenia rudis, F., 27 ; Muscina stabulans, Fin., 14 ; Musca 

 domestica, L., 12 ; Pyrellia eriophthalma, Macq., 12 ; Musca corvina, 

 F., 9 ; Li?nnophora septemnotata, Ztt., 6 ; Calliphora erythrocephala, 

 Mg., 3 ; Fannia canicularis, L., 3 ; Phaonia signata, Mg., 2 ; Phorbia 

 muscaria, Mg., 1 ; Muscina pabulorum, Fin., 1 ; Chloropisca notata, 

 Mg., 1 ; Blepharoptera serrata, L., 1 ; Tephrochlamis canescens, Mg., 1. 

 The notes as to the conditions under which they were found afford no 

 support to the belief that house-flies hibernate in this country in the 

 adult state. The few specimens of Miisca domestica sent in were all 

 taken in an active condition ; some of the other flies, however, such 

 as the extremely common Pollenia rudis, ¥., were often found partially 

 dormant. It is difficult to resist the conclusion that, did the house-fly 

 really hibernate in the adult state, some evidence of the fact must 

 have been obtained. The idea suggests itself that the relative lateness 

 of the season at which house-flies annually become abundant may be 

 due to the smallness of the number of individuals that, in an active 

 condition, survive the winter in houses and other buildings, although 

 it must be admitted that there is as yet nothing in the shape of proof 

 that female house-flies found alive at the end of winter actually survive 

 until oviposition takes place. The suggestion here made is not neces- 

 sarily invalidated by the apparent discrepancy provided by the case 

 of the lesser house-fly {Fannia canicidaris, L.), which contrives to 

 establish itself in some numbers in houses considerably earlier in the 

 year than Musca domestica, although in the case of this species also 

 there is no evidence that it hibernates there. The preliminary stages 

 of the two species mentioned are very different and it by no means 

 follows that the winter is passed in both cases, in the same stage. 

 The numbers of the sexes of the 12 specimens of Musca domestica 

 were equal. 



Bernstein (J. M.). ii. The Destruction of Flies by means of Bacterial 

 Cultures, pp. 27-31. 

 Hesse's experiments on Mucor raceynosus which constantly resulted 

 from attempts to cultivate Empusa muscae led him to try the former 

 upon flies. He met with success both on captured and on bred flies, 

 and polymorphism of these two fungi therefore suggested itself. 

 Further and careful experiments only resulted in the constant pro- 

 duction of Mucor raceniosus. The author cultivated the fungus by 

 Hesse's method on shces of yolk of egg steriHsed at 100° C. from flies 

 dead of Emyusa muscae and made a series of experiments with it. 

 All his flies, bred from insects in confinement, died of Empusa muscae 



