Dogbane and Milkweed 313 
The bee seems the favorite guest of the milk- 
weed. The pollen-masses come out at once to her 
tread, and are carried directly to the pistil of 
another flower. 
Wasps visit the milkweed for its honey, but I 
have never seen them withdraw the pollen-masses. 
Flies seldom do, though the flower is visited by 
flies of many species. Indeed, it is a general 
favorite, standing in the midst of a winged throng 
till dark, for twilight brings to it a number of 
small, sad-colored moths with very long proboscides. 
But not all these visitors are permitted to go in 
peace. A small fly with his legs stuck to the 
black disks is frequently unable to pull himself 
loose after he has drunk his fill. 
In a bunch of twenty-five blossoms I have 
counted five flies.thus held in captivity—three 
dead and two dying—and the same bunch had 
captured a long-legged, lace-winged caperer, whose 
struggles to free himself were as desperate as futile. 
On any large bunch of these flowers one can see 
mementoes of past tribulations. Here and there 
a blossom still holds a little black leg, the price 
of the liberty of some insect who has gone off 
free, but a cripple. 
A flower so highly organized as the milkweed 
