49 LIFE HISTORY OF NORTH AMERICAN TICKS. 
the ixodid ticks often fail to hatch when not supplied with moisture 
during periods of excessive heat in summer or during dry winters 
when the incubation period is very long. Flooding apparently has 
little influence in controlling ixodid ticks, as the larve of M. annu- 
latus have been found by Hunter and Hooker (1907) to survive a 
submergence of from 10 to 157 days. Vorontzov (1907) states that 
the eggs of Ixodes ricinus may retain their vitality under water from 
fall to spring, and Hunter and Hooker have found the eggs of I. 
annulatus, when submerged, to hatch in about the normal period. 
PREDACEOUS ENEMIES. 
Sowbugs, which have been supposed to destroy eggs of ticks, have 
been shown by Pierce (1907, pp. 17 and 22) to consume compara- 
tively small numbers even when confined with no other source of food 
supply. Solenopsis geminata, an ant widely disseminated in this 
country, is thought to be an important enemy of ticks. Rats and 
mice feed upon ticks and field mice undoubtedly assist in a limited 
way in destroying the engorged females. Wellman (1906b) has 
observed a reduviid bug (Reduvius [Opsicxtus] personatus) feeding on 
engorged ticks in Africa. 
Domestic fowls have been found to destroy cattle ticks that drop 
about farm buildings and even to jump up and pick them off dairy 
cows. A hen has been observed by the writers to devour with avid- - 
ity as many as 150 engorged females of Margaropus annulatus in a 
half day. Quite a number of species of birds have been observed to 
light on cattle and feed on the engorged ticks. Several species of 
blackbird, including the great-tailed grackle or ‘‘jackdaw” (Mega- 
quiscalus major macrourus), bronzed grackle (Quiscalus quiscula 
zneus), and Brewer’s blackbird (Huphagus cyanocephalus) are known 
to do so in Texas. Kingbirds (Zyrannus tyrannus) have been ob- 
served to do this in Louisiana, and Newstead (1909) reports that in 
Jamaica the savannah blackbird or tinkling grackle (Quiscalus cras- 
sirostris) and the ani or ‘“‘parrot-billed blackbird” (Crotophaga ani) 
have the same habit. McAtee (1911a) states that Mr. H. S. Barber 
has observed red-eyed cowbirds (Tangavius zneus vnvolucratus), boat- 
tailed grackles ( Megaquiscalus major), and another species of black- 
bird picking ticks from cattle at Brownsville, Tex. At Tampico, 
Mexico, Bishopp observed the groove-billed ani (Crotophaga sulcirosiris) 
to feed upon Margaropus annulatus australis, attached to cattle. 
This species and the red-winged blackbird (Agelaius pheniceus) are 
said by Moreau (1907, figs. 8-9) to prey upon cattle ticks in Mexico. 
Cherry (1892, p. 325) states that the groove-billed ani habitually 
feeds upon cattle ticks in Costa Rica. Bendire (1895, p. 435) states 
that eastern cowbirds ( Molothrus ater) and McAtee (1911b, p. 401) says 
that the fish crow (Corvus ossifragus) eat ticks. Other birds in the 
