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.

    13/30 (page 9)
    out twenty-live days later (Marcli 30tli). The species proved to be that known as Eristalis arbustoruvi, L., which is much smaller than E. tenax, and very common in all parts of the British Islands. In the United States of America the discharge from the human bowel of lai'A'ce of Evistulis tstiux and E. dvintcl'icitus, A^^ied., has been recorded by the late Professor Biley.(^) In the latter of the two cases the patient was also a woman, and it is perhaps worthy of note that, althougdi the recorded instances of intestinal Myiasis due to larvte of species of Eristalis at present number only some live or six, at least three of these have been in women. That Dipterous larvse belonging to various families exhibit extraordinary powers of resistance to unfavourable conditions is well known; but that larvtB which live normally in cold water, and possess a respiratory apparatus of the peculiarly modified type prescribed above, should be capable of withstanding, and even existing for Aveeks in the temperature and other conditions obtaining in the human intestine seems truly remarkable.* Musca clomestica, L. (The House-Fly). My iasis due to the house-fiy would seem to be rare, or at any rate seldom reported, since only Wo instances—both intestinal and both in infants—have come under the author’s notice. In one of these cases, Avhich occurred in September, 1903, and from which specimens Avere submitted to the author for deterrnination by Dr. Hubert Armstrong, Honorary Assistant Physician to the Liverpool Infirmary for Children, larvae of Musca domestica of different ages, together with others belonging to Fannia canicularis, L. (the Lesser House-Fly—see below), were “ voided from the alimentary canal of a male infant aged seven months.” As stated in the author’s “ Table ” published in Eeport Ho. 5 of this series,(^) the House-Fly larva—a white footless maggot of the usual Muscid type—is distinguishable from similar larvae by the shape of the respiratory clefts in the stigmatic plates at the broader (posterior) end of the body. In the case of the larva of M. domestica these clefts, instead of being straight or * As illustrating the remarkable power of resistance to apparently unfavour- able conditions possessed by the larvae and pupae of Eristalis tenax, it may be mentioned that some years ago the British Museum (Natural Bistory) received a series of living pupae of this species, accompanied by the statement that the pupae had been found in numbers in new sheepskin rugs, purchased from a well-known London furnishing firm. In reply to enquiries, the firm in question stated that they obtained the rugs direct from the manufacturers in Ber- mondsey, taking them immediately they were dyed, so that it was clear that the pupae, if not the larvae, must have passed through the somewhat severe ordeal of the dyeing vats. An almost equally striking instance of indifference to the medium in the case of an allied species was recently recorded by Mr. C. G. Lamb, who stated that he had found living larvae of Eristalis aeneus, Scop., in rock pools containing salt water and rotting seaweed, and filled only at sjjring tides, at the north end of Constantine Bay, St. Merryn, Cornwall. “ The habitat,” wrote Mr. Lamb, “ is such that the pools are exposed for many consecutive days to the hot sun with- out any chance of replenishment of the water, so that the salinity must vary considerably, and this is apparently without harm to the larvae ” {cf. C. G, Lamb,