Ixodidae 



247 



suitable place. The larvae, hexapod and sexually indistinguishable, 

 infest rodents during June, July and August, require 4 to 7 days for 

 engorgement, then drop and molt to nymphs before the onset of cold 

 weather. After hibernating the octopod nymphs, also sexually indis- 

 tinguishable, infest rodents in April, May and June. On completing 

 engorgement, which requires 3 to 10 days, the nymphs leave the host 

 and molt to the adult stage during the summer. These adults normally 

 do not feed until the following spring. Thus the life cycle requires a 

 minimum of 2 years for completion. However, under unfavorable con- 

 ditions it may be extended to 3, and rarely to 4 years, because of the 

 resistance of the adult ticks to starvation. 



REARING ROOM 



The mass rearing of D. andcrsoni is conducted in a large room 

 (50' x 25') specially designed to prevent the escape of ticks and to elim- 

 inate, in so far as possible, places in the room in which ticks may remain 

 undetected. There is but one entrance. The floor is concrete, with drains. 

 The apertures surrounding all pipes passing through the floor are tick 

 proofed as shown in 

 longitudinal section in 

 Figure 48. The walls 

 are finished with ce- 

 ment plaster to permit 

 washing down and win- 

 dows are specially de- 

 signed and tightly 

 screened with 18 mesh 

 wire cloth. The sash 

 weight boxes are tick 

 tight and crevices be- 

 tween the window 

 frames and walls are 

 packed with oakum. 

 The floor and walls 

 are flushed daily with 

 near-boiling water 

 under pressure to kill 

 or remove ticks which 

 may be free in the 

 room. The tempera- 

 ture is maintained 



automatically at 2 1 FjG 4g — showing method of tick proofing apertures 

 C. or slightly above. around pipes passing through floor in tick rearing room. 



floor Leve/ 



