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.

    10/30 (page 6)
    i^'amily Muscid^. (Subfamily Muscinse.) Musca domestica, L. (The House-Fly). (Subfamily Anthomyinse.) Fanma canicularis^ L. (The Lesser House-Fly). Fannia scalaris, F. Anthomyia radicum, L. Family Tachinid^. Subfamily Calliphorinse. Calliphora or Lumlia sp. (Blow-Flies or ^‘Green-Bottle^’ Flies). Family Sepsidje. Piophila casei, L. (The Cheese-Maggot Fly). It will be observed that the above list includes no representa- tives of the Bot- and Warble-Flies, which in the larval stage are normally parasitic in domesticated and other mammals. No British cases of Myiasis in man certainly due to these flies are known to the writer, although the occasional infestation of human beings by the larvae of various species of Bot- and Warble-Flies has frequently been recorded on the continent of Europe, in Algeria, and in North and South America. Human Myiasis in the British Islands must be regarded as being for the most part of accidental occurrence, being due to larvae which are not habitual parasites but wont to lead a free and independent existence, in many cases living and feeding in dead, decaying, or fermenting animal or vegetable matter, or in excrement. The species mentioned in the foregoing list will now be considered in detail, in connection with cases of Myiasis in which their larvae were concerned. Tliereva sp. incert (? nohilitata, F.). The genus Tliereva, which has no English name, though eight recognised species are known to occur in the British Islands, consists of medium-sized, dusky flies, with rather elongate bodies somewhat pointed at the posterior extremity, and clothed, especially in the male sex, with outstanding, furry hair, which varies in hue according to the species and may conceal the ground colour. The adult insects, which feed chiefly on other flies, are found on the leaves of bushes, on the foliage of large-leaved plants, or resting on earth or sand, and two species, T. pleheia, L., and T. nohilitata, F., are not uncommon in gardens. The larvae, which are very active, glistening white, slender, worm-like creatures, with small dark brown heads, may measure about an inch in length; owing to a series of peculiar constrictions en- circling the body, they apparently consist of nineteen or twenty segments. They live in garden mould, earth, sand, or decaying Avood, where they are said to feed upon other insects or upon vegetable matter, &c., so that their occasional transference to the human alimentary canal, doubtless through the medium of uncooked vegetables, is not difficult to understand. On July 22, 1904, the author received for examination from a medical man in Hampshire a living larva of a species of Tliereva —very possibly T. nohilitata, F., accompanied by the statement that the specimen had been coughed up b} a man who had