BULLETIN 553, U. S. DEPARTMENT OF AGRICULTURE. 



fertilization can take place soon after molting and before feeding, 

 and it can take place also after feeding. Directly after molting 

 the females will feed, but the males will not. No doubt each male 

 is able to fertilize several females, so that immediately after molt- 

 ing this is all the male 

 desires. Xormally ferti- 

 lization takes place off the 

 host, though it is conceiv- 

 able that occasionally it 

 may take place on the 

 host. The females begin 

 depositing eggs within 

 about 12 hours after feed- 

 ing. They will feed and 

 deposit fertile eggs re- 

 peatedly with only one 

 fertilization. Under ob- 

 servation this was done 

 eight times. No doubt 

 under natural conditions 

 these females would have 

 been visited by males sev- 

 eral times. A single feed- 

 ing during warm weather 

 is all that is necessary for 

 each deposition. A very 

 small number of mites 

 failed to oviposit after having had one good feeding. An engorged 

 female is shown in figure 2. 



Fig. 2. — The chicken mite : Female mite engorged 

 with blood. Greatly enlarged. (Bishopp and 

 Wood.) 



LIFE-CYCLE EXPERIMENTS. 



The following outline gives an accurate record of the life cycle as 

 worked out at Dallas, Tex. : 



First-stage nymph engorgement : 



August 6, 6 p. m. Several hundred first-stage nymphs put in jar with fowl. 



August 7, 9 a. m. 542 engorged first-stage nymphs recovered. 

 First-stage nymph molting: 



August 8, 7.30 a. m. Many have molted to second-stage nymphs. 

 Second-stage nymph engorgement : 



August 9, 5.30 p. m. All the second-stage nymphs (perhaps 50 of the 542 died) 

 put in jar with chicken. The nymphs are very active. 



August 10, 9 a. m. 263 engorged nymphs recovered. 

 Second-stage nymph molting and mating: 



August 11, 9 a. m. Many have molted. Several pairs found to be in position 

 of copulation. 



