252 



Phylum Arthropoda 



& 



p IG _ S4 . — Diagram of "tick picker" used in recovering fed 

 immature ticks from the animal cage bags. 



removable cup C, the bottom of which is made of 

 brass gauze. The screens are removed and placed 

 on edge in D, the bottom of which is open, where 

 they are cleaned by washing with water from a 

 hose. The volume of larvae collected is meas- 

 ured in cubic centimeters, i cc. equaling ap- 

 proximately 700 ticks. An average of about 

 5,600 ticks per rabbit is obtained in routine feed- 

 ings. The engorged larvae in quantities of 10 cc. 

 each are placed in glass cylinders i%" in di- 

 ameter and 4" in length, their escape being pre- 

 vented by pieces of muslin securely taped or tied 

 over the ends (Fig. 55). After being held from 

 4 to 5 weeks in thermal cabinets at 22 ° C. and 

 relative humidity about 50%, the larvae will 

 have molted to nymphs and the latter be ready to 

 feed. 



Engorging of Nymphs. The procedure fol- 



A "tick picker" 

 (Fig. 54) is used 

 in recovering fed 

 immature ticks 

 from the bags in 

 which they are 

 contained after 

 dropping from the 

 animals. It is 

 made of galva- 

 nized sheet metal 

 with dimensions 

 as illustrated. 

 The bags are re- 

 moved from the 

 cages, turned in- 

 side out and 

 shaken in the hop- 

 per. Removable 

 screen A, 6 mesh, 

 and B, 14 mesh, 

 retain the trash 

 while the engorged 

 larvae fall through 

 and are caught in 



Fig. 55. — Diagram of 

 pyrex cylinder in which 

 fed larvae are held for 

 molting. 



