29 



(1938) was fairly complete at the time, but since he could not colonize 

 the mite past the larval stage, he could not fully describe the 'life 

 cycle. Colonization has since been accomplished (Chamberlain and S i kes , 

 1 9 5 ; Cross, 1954; Cross and Wharton, 1964), and the* entire lire cycle 

 has been described (Sikes and Chamberlain, 1954; Soulsby, 1968). Accord- 

 ing to Sikes and Chamberlain (1954), females lay an average of two to 

 three eggs, each one within 43 hours after a blood meal. Eggs hatch in 

 less than 1 day to six-legged non-feeding larvae which molt in less than 

 1 day to eight-legged protonymohs. Protonymphs take an average of 2 

 days in which to require the two blood meals necessary for full engorge- 

 ment. Protonymphs molt to non-feeding deutonymphs that molt to adults 

 in about a day and a half. Time from adult engorgement to second genera- 

 tion adult was about 5 to 7 days at 38 to 40 C with a relative humidity 

 of 90 to 100%. Length of the cycle varies at least partly due to the 

 intermittant feeding habits of the mites (Cameron, 1938). 



The whole life cycle of 0. syZvtarum occurs on the host (Sikes and 

 Chamberlain, 1954; Kirkwood, 1968; Loomis, 1978); however, oviposit ion 

 may occur in the nest of the host (Cameron, 1938). Even though the 

 northern fowl mite has long been considered a winter pest (Loomis. 1978)., 

 mites have been found on chickens all year round (Kirkwood, 1963 snu 

 1968), and will come out to the tips of the feathers in hot weather 

 (Cameron, 1933). When separated from the host, 0. s^lviarr-an will live 

 from 2 to 4 weeks (Cameron, 1938; Baker et al., 1956; Kirkwood, !9o3; 

 Loomis, 1973), as compared to 34 weeks for Dexmanyssus gaZZ-inae 

 (Kirkwood, 1963). 



