193 LIFE HISTORY OF NORTH AMERICAN TICKS. 
TaBLe XLIV.—Summary of parasitic periods of Margaropus annulatus australis— 
Continued. 
Females dropped. 
Infestation. First. — Period 
SS OM OTE, 
Wate Parasitic Hake Parasitic pales tn 
period. period. 
ee —_— |} $$$ —$ 
LIFE CYCLE. 
Under favorable conditions the progeny of a single tick may survive 
for a period of 82 days from the date hatching commences. The 
larvee usually molt on the sixth day following attachment to the 
host, although in some instances as many as 9 days may be required. 
The nymphs usually molt in from 8 to 10 days later, but as many 
as 13 days have been observed to be required in some instances. 
Adults have been found to engorge in 7 days. In our observations 
the last females dropped engorged on the twenty-ninth day from 
attachment, but the period would probably be longer if males were 
not present. In one instance oviposition commenced on the day 
following dropping, but usually several days pass before such takes 
place. In June, at a mean temperature of 78° F., hatching began 
on the twenty-third day. An effective temperature of 834° F. 
appears to be required for incubation. 
ECONOMIC IMPORTANCE. 
This tick is so closely related to our species (Margaropus annulatus) 
that what has been said of annulatus proper regarding its impor- 
tance as a pest may also apply to it. Im the countries where it 
occurs australis is the same great pest that annulatus is in the 
southern United States, and transmits Piroplasma bigeminum in a 
similar manner. The habit of the larve in attaching to man, how- 
ever, adds to its importance. 
NATURAL CONTROL. 
As with annulatus, birds (particularly blackbirds), mice, ants, 
toads, and lizards are probably its principal natural enemies. In 
Jamaica, the tinkling grackle (Quiscalus crassirostris), and the ani or 
‘narrot-billed blackbird”’ (Crotophaga ant) are reported by Newstead 
(1909) to be its principal bird enemies. 
Ds ee ee ee, ee 
