90 
Biology of Ixodidae 
5—9 days after the replete female abandons the host in summer and the 
process lasts 11-40 days at 15-19° C., during which time the female lays 
450 to 830 eggs, the average number being 600. The small number of 
eggs laid is in accordance with what I expected, that Ixodes parasitic 
upon hosts with fixed habitats lay fewer eggs since they are less exposed 
to loss of life than species occurring upon wandering hosts. The time 
required for metamorphosis from the egg to the larval stage is 30-49 
days at 15-19° C. The larva may survive unfed for 348 days and males 
live up to 123 days in a corked bottle at room temperature in the 
presence of a slight degree of moisture. The longevity of unfed nymphs 
and females remains to be determined as well as the period which the 
different stages remain upon the host. 
IXODES HEXAGONUS. 
Observations made on nymphs and females etc. obtained 13. iii. 1911 
from a ferret in Cambridge. 
Time required for metamorphosis. 
Egp to Larva. Data relating to the progeny of the two females whose records follow. 
The time is reckoned from the date on which the female began ovipositing to the day 
on which the first larvae emerged. 
Progeny of 
Larvae 
¥ No! 
Eggs laid on 
emerged on 
Time in days 
1 
27. IV. 1911 
9. VII. 1911 
73 at 13-18-.5° C 
2 
21. IV. 1911 
1. VIII. 1911 
102 
Larva to Nymph. 
No observations recorded as repeated efforts to raise these and otlier 
lots of larvae 
on hedgehogs and other 
ordinary hosts failed. 
Nymph to Adult. 
Collected gorged on 
Adults emerged on 
Time in days 
2 Nymphs 
13. HI. 1911 
29. V. 1911 (2 ?’s) 
77 at 13-18-5° C. 
Longevity of unfed females. 
The two females which emerged from the foregoing nymphs were placed in a wooden 
pill-box on slightly dampened earth. The one lived for 9 days, the other over 42 days 
(18. X. 1911) at av. of 15° C. 
Observations relating to oviposition. 
Bate when 
dropped 
Began to 
oviposit 
after 
Oviposition 
lasted 
Female sur¬ 
vived after ovi¬ 
No. of 
eggs 
Temperature at 
which ticks were 
¥ No. 
from ferret 
position ended 
laid 
maintained 
1 
13. HI. 1911 
45 days 
32 days 
6 days 
650 
av. 9°C. 
2 
9 9 
39 days 
— 
— 
2.50 
9 9 
