LIBRARY

780 COLLEGE ENTOMOLOGY
obviously unknown to the bees. According to Phillips about 20 days are required
for development. The adults emerge from pupre either in or outside the
cells of the larval bees. They not only ride the bees but are considered to be
annoying robbers or highly specialized ectoparasites. They are able to procure
food from the bees by clawing at their mouth parts, and this and other irrita.
tions are thought to injure the hosts. Bees, especially the queens which are
particularly attractive to them, appear to generally disregard them although
the stronger and more active workers have been observed to rub them off their
FIG. 286. The bee lotlse, Brmlla creca Nitzsch, un old world ectoparasite of the honeybee
rarely taken in North America. (Drawing by E. S. Ross.)
bodies. The species now appears to be most abundant in parts of southern
Europe but has been widely distributed and is known to occur in parts of eastern
North America, South America, Tasmania, South Africa, Japan, and possibly
elsewhere. It was first noted in North America in Pennsylvania by E. H. Bess
in 1918 and does not appear to have spread very rapidly. Several species have
been described, but they are generally supposed to be forms of the common
bee louse described above.
FamilyPLATYPEZIDAl: Walker 1851 (Plat'y-pez'i.dre, from the Greek 7rAIJ.TVS,
broad, wide, + 7rerIJ., foot; because of the wide hind tarsi). German,
Tummelfliegen, Rollfliegen. Flat-footed Flies.
The adults are small, 2-4 mm., thinly haired and bristled, somber-colored
flies characterized by enlarged and flattened hind tarsi which are ornamented
in some of the males The eyes are often holoptic. Ocelli present. Antennre
three-segmented, with a long dorsal or terminal arista. Tibire spurless. The
larvre are wide and flattened; pale-colored; with lateral, segmented, spiniferous
processes on all the segments except the first, second, and last. They live and