B12 THE BLOWFLIES OF NortH AMERICA 
evidence to suggest that the species is physiologically unable to 
act in the role of a primary invader in subdermal myiasis. 
Pupa. Possessing the external characters of the mature larva. 
Bishopp (1915) stated that the pupal period of this species lasts 
from 7 to 9 days in Texas. 
The larvae pupate in soil at a depth of from 114 to 2 inches 
according to Roberts (1930), who also found that adults would 
emerge from puparia buried at a depth of 18 inches of closely 
packed, fine, sandy soil. 
Adult. The slow-flying and loud-buzzing blue bottle fly of 
early spring and late fall is usually this species. It is commonly 
found in houses during the cooler seasons of the year and may 
sometimes become a nuisance to housewives under such circum- 
stances. It may be collected upon foliage in urban areas, and 
females commonly occur about carrion or other types of refuse. 
In the cool weather of early spring specimens may be seen upon 
the sunny sides of buildings or on rocks. Adults of vicina are 
attracted to any ill-smelling product of decay. During warm 
days in late November I have often collected many specimens of 
vicina which were feeding upon wind fallen apples in my gar- 
den. Carrion is by far the most satisfactory attrahent. 
The preoviposition period lasts as long as three or four weeks 
according to Lowne (1890-1892) who stated that this is ‘‘a con- 
dition which probably prevents the fertilization of females by 
males of the same brood.’’ The males are apparently sexually 
mature within a few hours. 
Hibernation in Australia seems to be accomplished in the 
pupal stage according to Holdaway and Smith (19382). 
Various parasites have been recorded as attacking this blow- 
fly. In England, Graham-Smith (1919) found two species of 
ichneumon-flies to be parasitic upon puparia of vicina. These 
were Phygadenon speculator Thomson and Acractodes bicolor 
Gravenhorst. He also observed that adults were occasionally at- 
tacked by a fungus disease. He noted that 61 percent of the 
autumn pupae were parasitized by Alysia manducator (Panzer) 
and 71 percent of the spring pupae by Melttobia acasta 
(Walker). James (1928) also claimed a reduction of 30 percent 
of the numbers of this species due to larval parasitism by the 
eynipids Figites anthomyiarum Bouché and Klewdotoma mar- 
shalli Cameron. 
The average time between ‘‘parental and filial emergence’’ is 
between 33 and 88 days according to Wardle (1927), the abso- 
lute minimum being not less than 29 days at the mean tempera- 
ture prevailing in England throughout the summer. Bishopp 
