THE CHICKEN MITE. 13 



measurements were made before and after the chance to feed on egg 

 was offered the mites, but there was practically no change except in 

 the case of one female which increased in length 71.75 microns and 

 in width 100.45 microns. Some of the same mites which refused to 

 feed on the cracked egg fed on a fowl when the chance" was given 

 them. The experiment indicates that mites rarely take nourishment 

 in this way. 



CONDITIONS FAVORABLE FOR PROPAGATION OF MITES. 



The two conditions most favorable for the propagation of mites 

 are (1) frequent direct and easy access to the fowls, and (2) nu- 

 merous hiding places, such as a complicated roost, dirt, litter, etc. 

 Other favorable conditions are the allowing of dirt and refuse to 

 collect without removal for several weeks. Darkness and dampness 

 without doubt help the mite to live longer in the absence of food. 

 Even under the most sanitary conditions it is able to increase and 

 multiply, so that cleanliness alone is not sufficient to rid premises of 

 the mite, although it is one of the first things to be sought when an 

 attempt at extermination is made because of the greater effectiveness 

 of insecticides when applied. 



SUMMARY OF LIFE HISTORY. 



Blood is the necessary food of the mite in all stages except the 

 larva, in which stage no food is taken. 



It takes about one-half hour to one hour for the mite to get its full 

 feeding and leave the fowl. The mite ordinarily crawls off the fowl 

 onto the roost or other near-by place, where it finds a convenient crack 

 or crevice in which oviposition, molting, and mating take place. Fe- 

 males deposit an average of four eggs each at the rate of four eggs in 

 24 hours. After finishing deposition the females feed again, usually 

 at night, one engorgement nearly always being sufficient for each 

 deposition. When full of blood the female is elliptical in outline, 

 plump, and blood red (see fig. 2). Females will continue to feed and 

 deposit eight times at least, and possibly many more times. The 

 female must copulate at least once before she will deposit fertile 

 eggs, although fertilization is not necessary before each deposition. 

 The male does not feed immediately upon molting as does the female, 

 but stays in the cracks, no doubt to fertilize several females. The 

 proportion of males to females is about one to two. The eggs hatch 

 in two days (August). The larvae, which have only three pairs of 

 legs, molt without feeding in about one day. The first meal is taken 

 as a first-stage nymph. The first-stage nymph before feeding is light 

 colored, like the larva, but is much more active. It becomes engorged 



