THE IGUANA TICK. 131 
0.9 mm. long by 0.6 mm. wide. The color varies as does that of the 
nymphs, a somewhat higher percentage of this species than others 
having a light gray color. A few have a pink color when they drop. 
Egg.—Ellipsoidal, light brown, shining, smooth. The maximum 
size for 10 was 0.677 by 0.570 mm., the minimum 0.631 by 0.539 mm., 
with an average of 0.652 by 0.560 mm. 
HOST RELATIONSHIP. 
The type host is not known. This tick attaches to cold-blooded 
animals, particularly iguanas and toads, upon both of which it 
engorged at Dallas. The toad, however, died before the larve all 
engorged, due to being confined in a cage. In rearing experiments 
the larve and nymphs readily attached to and engorged upon a 
bovine, but the adults would attach to cold-blooded hosts only. It 
thus seems probable that in nature the immature stages attach to 
both cold and warm blooded animals and that the adults attach 
only to the former class. Newstead states that in Jamaica it is 
apparently confined to the common toad or so-called ‘ bullfrog” of 
the island (Bufo marinus). 
GEOGRAPHICAL DISTRIBUTION. 
The type locality is Mexico. During 1907 nymphs and adults of 
this species were collected by one of the authors (Wood) from iguanas 
which had been brought to Brownsville, Tex., from the Isthmus of 
Tehuantepec. The species has been recorded from Mexico, Guate- * 
mala, Honduras, Nicaragua, Panama, Jamaica, Antigua, Barbados, 
Trinidad, Colombia, Venezuela, Guiana, Brazil, Paraguay, Argentina, 
and the Philippine Islands. 
LIFE HISTORY. 
- The only information upon the biology of this tick that the authors 
have found is furnished by Newstead (1909). This author is in 
error in supposing that the molts are passed upon the host, as such 
is not the case. 
Egg (Tables XLVIII, XLIX).—In the laboratory in June and July 
at a mean temperature of 82° to 86° F. oviposition commenced 
on the sixth day after dropping and continued for 16 and 17 days. 
The larger number of eggs deposited by the two females from which 
counts were made was 1,655. Newstead (1909, p. 446), however, 
records 1,784 from one female, deposition commencing on the seventh 
day and continuing for 17 days. The minimum incubation period 
recorded by us was 27 days. This record was made on eggs deposited 
early in August. The mean temperature during incubation was 
85° F. An effective temperature of 1,133° F. appears to be required 
for the incubation of the eggs. The first tick, the oviposition of which 
