130 LIFE HISTORY OF NORTH AMERICAN TICKS. 
recorded was 81 days. At the end of this period one specimen was 
still able to attach to the host. On a warm-blooded host the nymphs 
may engorge in 8 days and molting may commence as soon as 29 
days after dropping. <A total effective temperature of 1,104° F. 
appears to be required to produce this molt. Adults may live for 90 
days and engorge as soon as 20 days after application to a host. 
Oviposition may commence as soon as the eighth day after dropping 
and as many as 5,481 eggs may be deposited. The minimum incu- 
bation period recorded (in winter) was 92 days. During this period 
a total effective temperature of 2,474° F. was accumulated. 
ECONOMIC IMPORTANCE. 
While this tick has not been considered of economic importance, 
the fact that it occurs on cattle and in large numbers on dogs and 
certain small mammals suggests the possibility of its becoming so. 
NATURAL CONTROL. 
No particular enemies of this tick have been observed. However, 
in experiments several ticks were lost by being devoured by the 
tortoise. 
THE IGUANA TICK. 
Amblyomma dissimile Koch. 
The common name of this species is given it because the iguana 
was the first animal upon which we collected it as well as being one 
of its most common hosts. Newstead (1909, p. 445) has made use 
of the name “bullfrog tick.” 
DESCRIPTIVE. 
Adult (Pl. X, figs. 3-5) —Males from 4 by 2.75 mm. to 5.25 by 
3.33 mm. Females, unengorged, from 4 by 2.5 mm. to 5.5 by 3.75 
mm.; engorged, from 14 by 9 by5 mm. to 17 by 10 by6mm. New- 
stead has described the coloration of the engorged female as ochreous 
to yellowish gray; scutum chocolate brown with dyil coppery mark- 
ings, forming a distinct spot at the apex. 
Nymph (Pl. X, fig. 2).—Unengorged, about 2 by 1.1 mm.; color 
varying from light to a darker brown. Length of capitulum 0.497 
mm. (from tip of palpi to base of emargination of scutum); scutum 
0.737 mm. long by 0.983 mm. wide. Engorged, from 4.5 by 3 by 2 
mm. to 5 by 3.25 by2 mm. The color varies according to whether 
blood or lymph has been engorged, the lymph giving a light gray, and 
the blood a brownish yellow color. 
Larva (Pl. X, fig. 1) —Unengorged, from 0.867 by 0.578 mm. to 
0.961 by 0.617 mm.; engorged, 2 by 1.15 mm. Capitulum 0.236 mm. 
long (from tip of palpi to base of emargination of scutum); scutum 
