Further reports (no. 5) on flies as carriers of infection.

Date:
1912
Catalogue details

Licence: In copyright

Credit: Further reports (no. 5) on flies as carriers of infection. Source: Wellcome Collection.

    20/30 (page 16)
    tlian M. domestica for a sliort time clmiug* the early part of the summer, especially in May and fTune. With the heginning of tlie hot weather the numbers of the latter increase enormously and replace the L('sser Honse-Fly. In many cases which were observed the latter seemed to retreat in small numbers to rooms of the house not devoted to cooking and they may be frequently found flying in a characteristic jerky and hovering manner around chandeliers, &c., in the living and bed-rooms. In country houses, however, they frequently occur in numbers in the kitchens as an examination of fly traps and papers in such places indicates. The numerical abundance of F. canicularis in comparison with M. domestica varies considerably. In a collection of nearly 4,000 flies which was made in different situations such as kitchens, restaurants, bed-rooms, &c., in 1907, this species formed 11’5 per cent, of the number. In 1900, Howard (TJ.S.A.) found that only about 1 per cent, of a collection of over 23,000 flies made in rooms where food was exposed were F. canicularis and over 98 per cent, were M. domestica. Hamer, in 1908, in collections made in kitchens and “ living rooms ” of houses in London, near depots for horse manure, found that the percentage of F. cani- cularis varied from 17 to 24 per cent. Niven gives the results of collections made at six different stations in Manchester. The total number of flies caught was 8,553 of which 8,196 were M. domestica, 293 F. canicularis and 64 were other species. Thus, F. canicularis constituted 3*4 per cent, of the total fly population. Robertson gives the results of similar collections made in Birmingham where, of 24,572 flies caught, 91 per cent, were M. domestica and 4’7 per cent, were F. canicularis. From observations that I have made in many localities in different neighbourhoods, I do not think that this species would often form more than 25 per cent, of the total fly population. After M. domestica, however, it is the next fly of importance inhabiting houses and well deserves the title of Lesser House-fly. It is known in Germany as ‘‘ die kleine Stubenfliege.” For a brief technical description of this species the Table by Mr. E. E. Austen in the first of the series of Reports on “ Flies as Carriers of Infection ” may he consulted. Proportion of sexes. Great disparity in the proportion of males to females is found in this species as it occurs in houses. Hamer showed in 1909 that the males constituted from 75 to 85 per cent, of tlie total flies of this species caught in balloons and on fly papers. This, however, does not indicate a disparity in the proportion of males to females in the species, as I have fomid that the females are more commonly found out of doors, especially in the neighbour- hood of the breeding places. Breeding habits. The breeding habits of this species are somewhat similar to those of the House-fly, Musca domestica. The eggs are laid in decaying and fermenting vegetable and animal matter and also