518 FLY MAGGOTS AND MYIASIS 



as 300 maggots have been taken from the skin of a puppy, and 

 it is not unusual for 20 or more to be present at once in a human 

 being. They come to rest just under the surface of the skin, 

 where they give rise in a few days to an inflamed boil, the in- 

 flammation being due to the movements of the spiny worm, and 

 to the presence of toxic excretions. As in the case of Dermatobia, 

 an opening is left to the surface of the skin from which the larva 

 obtains air through the spiracles at the posterior end of the body. 

 In some cases very little discomfort is felt from the maggots, 

 but in other cases an intense pain is caused at intervals. 



The larva is a fat, creamy-white maggot which reaches a 

 length of half an inch when full grown. It is bluntly pointed 

 at the anterior end but broad at the posterior end. The body 

 is thickly covered with minute dark brown spines, each one re- 

 curved like a rose thorn. 



Maturity is reached in about two weeks or less from the time 

 the infestation occurs, though usualiy the time is underestimated, 

 due to the fact that the larva is not noticed during the early part 

 of its existence in the skin. When fully developed the larva 

 voluntarily leaves its host and falls to the ground to pupate. 

 The pupa is of the usual barrel-shaped form characteristic of 

 the group of flies to which this species belongs. It is a little 

 less than half an inch in length, at first of a light rusty color, 

 later turning dark purplish brown. The adult insect emerges 

 from the pupal case in about two weeks. 



Preventive measures against the fly consist to some extent in 

 personal cleanliness, since it is doubtful if the flies will deposit 

 their offspring except on surfaces smelling of perspiration or other 

 body excretions. Infants seem to be especially subject to attack, 

 and should, therefore, be kept scrupulously clean. Since the 

 larva of the fly lives readily in many domestic and wild animals, 

 its extermination is hardly possible. In some parts of Africa, 

 notably in Natal, the worm becomes abundant for several 

 seasons, and then disappears for a number of years. The reason 

 for this is not understood. 



A closely allied fly, C. rodhaini, occurs in the damp equatorial 

 forests of Africa, attacking thin-skinned animals such as an- 

 telopes and rodents, and occasionally man. Dogs, cattle and 

 other thick-skinned animals are immune. The female of this 

 species may deposit over 500 eggs, which hatch f in from two to 



