520 



ILV MAGGOTS AND MYIASIS 



(Fig. 250B) arc white, footless creatures, provided with a pair 

 of stout hooks near the mouth, and with bands of minute spines 

 which give tliem a screwhke appearance, wlience they derive 

 their name. Eating away at flesh and even bone, they develop 

 rapidly to a length of about half an inch, and maturity may be 



reached in three days, 

 though four or five days is 

 usually recjuired. When 

 fully developed the larva 

 leaves its feeding grounds 

 and buries itself in loo.se 

 earth nearby, where it 

 pupates in two or three 

 daj's. T h e ]) u p iv a r e 

 brown in color, and shaped 

 somewhat like olives. After 

 four days or more in the 

 pupal case the adult insect 

 emerges, climbs up on 

 nearby herbage and rests in 

 a characteristic position 

 with the head down. The 

 whole life cycle occupies 

 from nine days to two 

 weeks or more. 



As remarked before, the female screw-worm fly, about to r(^- 

 produce, is attracted to anj'' animal smell and frequently finds a 

 suitable place for egg-laying in exposed wounds, or in the nose or 

 ears of people sleeping out doors, especially in case of foul-smell- 

 ing catarrh. Sometimes the flies select recently vacated Drr- 

 nintobin nests, boils, sores, etc., for the j'oung to develop in. .\s 

 soon as hatched the maggots begin eating their way into the 

 tissues with which they are in contact, using their strong man- 

 dibles as nippers for cutting flesh and even l)()nc. From the 

 car they may make their way into the inner ear, completely i\o- 

 Htroying the auditory apparatus. From the nose they penetrate 

 to the pharynx, frontal sinus, the eye-ball, and even the lirain, 

 occasionally doing such extensive damage as to cause death. 

 I'sually an abundant discharge of pus and scraps of tissue, in- 

 tense pain, and delirium accompany the infestation. A severe 



Fig. 2.50. Screw-worm fly, Cochliomyia (or 

 Chrysomyia) maccllarin, adult and maRgot. 

 X 3. (Adult aftiT Ca.stellani and Chalmers, 

 larva after Blanehard.) 



