MYIASIS 215 



bluish green colour. On the thorax there are three longitudinal 

 darker blue bands of a purplish tint. The larvae usually live in 

 decomposing animal matter. Hermes, who has carefully studied 

 their habits, states that they behave in much the same way as 

 the larva; of Z. ccFsai^ {see p. 25). 



The flies, however, occasionally deposit their eggs, or the 

 young living larvae, in great numbers in the ears or nasal fossae 

 of persons sleeping in the open air, especially if offensive 

 discharges are present, which attract the fly. The larvae burrow 

 into the tissues, devouring the mucous membrane and underlying 

 tissues, including the muscles, cartilages, periosteum, and even 

 the bones, thereby producing terrible sores. Sometimes they 

 invade the frontal sinuses, antrum and other cavities, causing 

 serious loss of substance and mutilation. If the patient is left 

 untreated they may penetrate into the brain and cause death. 



The larvae when full-fed measure 14 — 15 mm. in length. The 

 twelve segments of the body carry circles of minute circularly 

 arranged hooks, which give the larva a screw-like appearance, 

 from which the popular name, screw-worm, is derived. The 

 buccal cavity is armed with two powerful hooks, by means of 

 which the larva attacks the tissue, 



Pieter (1912) describes a case of infection of the vagina in an 

 old beggar woman. 



Animals are occasionally affected. 



An interesting case of infection of the nose with the larva; of 

 the Blow-fly {Calliphora erytJirocepJiald) is related by Lawrence 

 (1909). 



"Mrs B., aged 55, an asthmatic, while sitting sewing, felt a fly enter her right 

 nostril. She at once tried to expel it by blowing her nose, but without success." 

 Later the fly was discharged. Next morning there was a bloody nasal discharge. 

 The nose began to smell. The day after she could not leave her bed. The third 

 morning there was a foul sanious discharge, the swelling considerable, and the pain 

 and distress severe. Soon the patient's condition was serious. A week from the 

 time of infection some maggots were discharged and continued to come away for ten 

 days. " As the right ala became very much swollen, and blocked the passage it was 

 incised, and a small nest of maggots revealed. They spread into the right cheek up 

 to the lower eyelid; they burrowed into the gums, and appeared in the mouth." 

 Ultimately between 100^150 maggots passed out. "They left the nasal cavity 

 disorganised and the bone exposed in many directions." A blow-fly was hatched 

 from one of the maggots. 



