BIOLOGY AND CONTROL OF CHIGGERS. 7 



This examination of the small mammals of the infested area, it 

 should be noted, was made late in the season. It is possible that if 

 the trapping had been done earlier, different results would have been 

 obtained. During the summer of 1921 such trappings are planned 

 for the months of June and July. It will be interesting to observe 

 the results. 



Among other hosts held under suspicion were reptiles. Tortoises 

 were found in the vicinity of the infested area. These were caught 

 and examined, but no chigger larvae were found. Early in July, 

 1920, Mr. William Palmer, of the National Museum, captured a large 

 king snake, Lampropeltis getulus getulus, at Chesapeake Beach, Md., 

 that had hundreds of mite larvse attached to its skin, between the 

 scales. He brought the snake to the Museum, and when it was 

 shown to the writer a few days later it had molted. In the cast 

 skin were found hundreds of trombidiid larva? in various stages of 

 engorgement. An examination of these showed them to be no other 

 than the chigger that attacks / ^-^____— 



man along the Atlantic slope. pL S • • ■ 7~\~7~~"\ 



Parts of the cast skin with X^^-^,^.,^^^ .-'"•. \ 

 chiggers attached were placed X^ '^^Wk .••"..• f 



in breeding cells, and chig- ^— _ --"y J 



gers that appeared fully en- — ■ 



gorged were likewise placed in Fl f a "T^V^Tr/ ^ cMsger - mit 1 e 1 ^ rva 



to fc> i from the inside, X 1,200. Drawing made from 



breeding cells, but in neither specimen taken at Lake Minnetonka, Minn., 



case did any of the larvae ^^Sol* the University of Minne " 

 transform into nymphs. 



Those attached to the skin of the snake remained attached and 

 soon died unless forcibly removed. The actions of the chiggers 

 in remaining attached to the skin after the latter was cast and their 

 dying in this attached position would seem to show that the king 

 snake is not a natural host. Further, it is known that chiggers exist 

 in enormous numbers where very few snakes of any kind are found. 

 The determination of the natural hosts of our American clnVgers 

 has not been made. Further investigation along this line is needed. 



INJURY. 



CHIGGER INJURY CONFUSED WITH MANY OTHER KINDS OF INJURY. 



Of the many complaints about chiggers that have come to the 

 writer, a very large number, fully one-half in certain sections, were 

 found upon investigation to be due to hives, caused by the disagree- 

 ment of some food eaten and probably accentuated by hot weather. 

 A very large number of complaints supposed to be concerning 

 chigger attacks were found to be due to nettling from some thorned 

 plant. Serious attacks in a front lawn in Virginia, reported to be 



