The True Chiggers 



127 



^hy it should not become established in Florida and Texas. It is 

 usually believed that Brazil was its original home. Sometime about 

 the middle of the nineteenth century it was introduced into West 

 Africa and has spread across that continent. 



The males and the immature females of Dermatophilus penetrans 

 (fig. 93) closely resemble those of other fleas. They are very active 

 little brown insects about 1-1.2 mm. in size, which live in the dust of 

 native huts and stables, and in dry, sandy soil. In such places they 

 ■often occur in enormous numbers and become' a veritable plague. 



They attack not only man but various animals. According to 

 ■Castellani and Chalmers, "Perhaps the most noted feature is the way 



93. Dermatophilus penetrans. Much enlarged. After Karsten. 



in which it attacks pigs. On the Gold Coast it appeared to be largely 

 kept in existence by these animals. It is very easily captured in 

 the free state by taking a little pig with a pale abdomen, and placing 

 it on its back on the ground on which infected pigs are living. After 

 watching a few moments, a black speck will appear on the pig's 

 abdomen, and quickly another and another. These black specks are 

 jiggers which can easily be transferred to a test tube. On examina- 

 tion they will be found to be males and females in about equal 

 numbers." 



Both the males and females suck blood. That which characterize^ 

 this species as distinguished from other fleas attacking man is that 

 when the impregnated female attacks she burrows into the skin 

 and there swells until in a few days she has the size and appearance of 

 3, small pea (fig. 94). Where they are abundant, hundreds of the 



