THE SKIN 



247 



Screw Worm 



Of the dipterous group one only, the Campsomyia macellaria 

 (screw- worm), requires special mention. In some sections these 

 parasites cause considerable damage and some fatalities. The larva 

 only are parasitic, the adult female depositing the ova in wounds 

 or . damaged tissue. The ova hatch in from one to ten hours and 

 immediately begin to burrow into the surrounding tissues. The fully 

 developed larvte are about one-half an inch long and about one- 

 third the diameter of a lead pencil. The damage consists not only of 

 mechanically lacerating the tissues but also of carrying infection 



Fig. 55. piGMENTKD MOLE. Showing an ovoid pigmented area, with an ir- 

 regular nodular surface and containing a few long hairs. These pigmented 

 areas or moles cause little or no Inconvenience unless irritated by drugs 

 or surgical interference. 



into the surrounding tissues. The larvae remain in the tissue from 

 four to six days, then drop to the ground, where they undergo the 

 pupal metamorphosis. 



The time-honored treatment consists of curetting the wound, thus 

 removing all the larvae possible. It may be necessary to apply chloro- 

 form or some penetrating antiseptic to cause the larvae in the deeper 

 tissues to migrate to the surface, or at least to move energetically 

 in order that they may be located and removed. The wound should 

 be properly dressed and protected against future infestation. It is 



