(j<3 Obaervatlons on the Jlabifs o/' Certain Flics 



Consequently the futility of calculations based on the number of 

 larvae or of pupae per pound of iiiamire is apparent. 



6. In the majority of numure heaps, examined duriii<i the winter, 

 there was no evidence that the larvae preferred any particular part of 

 the heap; but in a few cases they seemed to show a slight preference for 

 those portions which received least light. 



7. On February 19th and 29th and on March Itli, i91(), several 

 Chelifers — Chernes nodosum — were found in diyisli cow manure, at a spot 

 in the heap which registered a temperature of 35'^ C. On March 4th some 

 were carrying their egg-masses. Large numbers of Ganiasid mites were 

 also found in the same heap. 



8. The following parasites were bred — from two pupae of Hydrotaea 

 dentipes, found in cow manure, 2 IchneiDnons {Atractodes tenebricosus, 

 Grav. ?, A. exilis, Hal. S)', from a third pupa of H. dentipes a Figitid; 

 from pupa of Lonchaea vaginalis or of Anthomyia radicum an Ichnemnon; 

 from 2 Calliphora-like pupae, found in an ash midden, 1 and 2 Figiiids 

 respectively; and from 3 pupae of Eristalis lenax 72 (10? and 62 cJ), 

 24 and 8 (5 c? and 3 ?) Proctotrypids — Diajdria conica, Fabre, were ex- 

 tracted dead (see Kieffer and Marshall, 1907, pp. 948-950). 



Observations on the Distribution of Flies during the 

 Summer and Autumn 1916. 



From July to September a certain number of places were visited to 

 ascertain whether the House-fly and other species were present, and 

 whether distance from a town or other houses affected the species or 

 numbers of Musca domestica. 



In some cases old fly papers and contents of traps were collected 

 and fresh fly papers hung up; in two instances ti-aps were set and baited; 

 and in all cases flies present were caught and examined. 



For this purpose the places examined were divided into five groups: 



(A) = Places in town (Cambridge). 



(B) = Places, other than houses, outside town near buildings. 



(C) = Places, other than houses, outside town far from buildings. 



(D) = Houses far from buildings. 



(E) = Houses near buildings. 



{A) During the summer the majority of M. domestica were found in 

 the neighbouihood of horse manure, and were found to linger longest in 

 artificially heated buildings, e.g. a bakery. The latest date on which a 

 house-fly was found in the former situation was December 2nd, on which 



