BIOLOGY AND CONTROL OF CHIGGERS. 11 



Attachment of chiggers followed irregularly within a few hours 

 after exposure. The itching which appeared during the latter part 

 of the first 24 hours following attachment grew in intensity. At 24 

 hours after attachment not a single papule had appeared at any one 

 of the 10 points of attachment. During the second day swelling 

 subsided, and the pinkish coloration around the puncture points was 

 followed, first by a light blood-red and later by a deep blood-red 

 color. The immediate area around each larva changed to a whitish 

 color, and the discolored area as a whole was large and in some cases 

 mottled with light and dark red. The itching sensation reached its 

 maximum the second day. 



During the third day after infestation most of the spots changed 

 from the pinkish or light blood red of the second day to a dark 

 blood-red or purplish red. At the end of the third day one-half of 

 the larvae had become detached. 



During the fourth day few changes were noticed. One more larva 

 had dropped off, and a few of the spots were observed to be lighter 

 in color than the day before. 



During the fifth day all the remaining larvse dropped off. Spots 

 retained most of their color and in four instances small water blisters 

 developed near the center of discolored spots. 



On the sixth day the color of the spots continued to fade and in 

 one instance was practically lost. 



During the seventh day several of the spots regained almost their 

 normal flesh color. Five water blisters were observed, but only one 

 was conspicuous. ; 



On the eighth day the discoloration had entirely disappeared in 

 one instance and almost so in two others. Two water blisters were 

 left. 3 



GENERAL DISTURBANCES. 



As has been known for many years, general disturbances fre- 

 quently follow serious attacks from chiggers. Among the most 

 serious of these is the development of a fever and a temporary up- 

 setting of certain nervous responses. Oudemans has recently called 

 attention (11, p. 10) to the narrative of Alfred Russel Wallace rela- 

 tive to the latter's experience with chiggers in the Malay Archipelago. 

 This eminent naturalist wrote: 



All the time I had been in Ceram I had suffered much frbni the irritating 

 bites of an invisible acarus, which is worse than mosquitoes, ants, and every 

 other pest, because it is impossible to guard against them. This last journey 

 in the forest left me covered from head to foot with inflamed lumps, which 

 after my return to Amboyna, produced a serious disease, confining me to the 

 house for nearly two months * * *. 



3 The appearance of these water blisters is well illustrated by Riley and Johannsen 

 (11, fig. 43). 



