SUBFAMILY POLLENIINAE 349 
the euticula and apparently feeds with the posterior spiracles 
exposed. It usually penetrates the host in the anterior portion 
in the region of the tenth segment or a few segments posterior 
to the eclitellum. All the larvae observed by DeCoursey entered 
the host from the dorsal side, usually in the intersegmental fur- 
rows, although a few entered thicker portions or through the 
elitellum. Parasitism usually oceurs within 1 or 2 days after 
exposure of the host to hatching larvae. The larval stage lasts 
for approximately 13 days during the month of June in the 
midwestern United States. | 
No investigator in North America has found the quiescent 
stage in the first-instar larva nor the feeding details of the 
larvae as reported by Keilin. 
Larvae of Pollenia rudis apparently have never been reared 
upon foods other than living earthworms. DeCoursey tried 
to feed them upon cow dung, horse manure, loam soil, clay soil, 
grass sod, decayed roots of grasses in soil, decayed wood, decay- 
ing meat, and dead earthworms. Tao (1927) reported that she 
was unable to rear first-instar larvae of this species upon any 
normal blowfly medium. Riley’s record (1883) of the rearing of 
Pollenia rudis from cow dung in Virginia is probably erroneous. 
In Europe, larvae of rudis are parasitized by Trichopria brevw- 
penms Kieff., according to Séguy (1934). 
Puparitum. Length 7 mm., diameter 2.5 mm., with the major 
external characters of the mature larva. 
When fully mature, the parasitic larva leaves the body of 
the host, which may or may not be dead, and pupates in the soil. 
Keilin (1915) found that the pupal stage lasts from 39 to 45 
days. In the United States, Webb and Hutchinson (1916) found 
it to last from 11 to 14 days. Keilin’s investigations were con- 
ducted during the fall months, while Webb and Hutchinson 
conducted their experiments during midsummer. 
Adult. There are apparently four generations of Pollenia 
rudis each year in the United States. Hibernating and newly 
emerging adults may be collected on warm days during any 
winter month. When the weather permits flight in the spring, 
the flies may be collected upon early flowering plants, decaying 
fruits, or souring sap of trees. Copulation evidently occurs at 
this time, for DeCoursey (1927) found no spermatozoa in the 
spermathecae of hibernating females and ovaries of such speci- 
mens were not developed. 
Pollenia rudis is a rather cumbersome, slow-flying insect and 
is one of the easiest blowflies to capture in a hand net. During 
