How Insects Cause or Carry Disease 53 



wild and domesticated animals and a few attack- 

 ing birds. 



One of the most important of these is the jigger- 

 flea or chigoe (Dermatophilus penetrans, Fig. 33). 

 Various other names such as chigger-flea, sand- 

 flea, jigger, chigger are also applied to this insect 

 as well as to a minute red mite that burrows into 

 the skin in much the same way as the female of 

 the flea. So although they are entirely different 

 creatures you can never tell from the common 

 name, whether it is the flea or the mite that is be- 

 ing referred to. Both the male and female jigger- 

 fleas feed on the host and hop on or off as do other 

 fleas, but when the female is ready to lay eggs 

 (Fig. 34), she burrows into the skin. Her pres- 

 ence there causes a swelling and usually an ulcer 

 which often becomes very serious, especially if the 

 insect should be crushed and the contents of the 

 body escape into the surrounding tissue. 



These little pests are found throughout tropical 

 and subtropical America and have been introduced 

 into Africa and from there have spread to India 

 and elsewhere. They attack almost all kinds of 

 animals as well as many birds, being of course a 

 source of great annoyance and no inconsiderable 

 loss. They are more apt to attack the feet of men, 

 especially those who go barefooted. Sometimes 



