ANIMAL PARASITES. 141 



INSECTS. 



Parasitic diptera, or two-winged flies, 

 Parasitic occupy an important position in relation 

 Diptera. to disease, since various species of this 

 order are harmful to man in a number of 

 ways. Besides the inconvenience that large numbers 

 of diptera cause by their bites (e.g., jigger- flea, bed- 

 bug, etc.), incidents which are not always unattended 

 with danger to health and life, others of this order may 

 burden the economy with their young. The latter is 

 accomplished in one of two ways: i. By depositing 

 their eggs or larvae either upon wounds or in cavities 

 (of the body) leading to the exterior, such as the nose, 

 ears, vagina, etc., or by placing them beneath the skin. 

 In all such instances the larvae feed in the places depos- 

 ited and cause such annoyance as their growth and 

 migrations excite. 



2. In other instances the eggs or larvae are taken 

 into the intestinal tract with food or drink, and are 

 voided in the feces. 



Myiasis is the technical term used to denote the con- 

 dition in man in which the larvae of diptera are 

 parasitic; and depending upon whether the larvae 

 (maggots) are upon the exterior or interior of the body 

 it is designated external or cutaneous, and internal 

 myiasis, respectively. Where maggots are found in the 

 stools care must be taken to exclude the possibility of 

 flies having had access to the stools, since living young 



