BN a a a a a Oh ke a te sil i " 
1899 | _ FLOWERS AND INSECTS 31 
explain such cases. Kerner says: ‘ The flowers of the common 
bryony, Bryonia dioica, are not less remarkable. They occur on 
two kinds of plants, z. ¢., on one plant are developed only stami- 
nate and on the other only pistillate flowers, and since the pollen 
is not powdery, and therefore not scattered by wind, it must be 
carried by insects from plant to plant if the ovules are to mature. 
But the flowers, especially the pistillate ones, are very insignifi- 
cant, green in color, with faint smell, and they are half hidden 
under the foliage. Many insects fly past them without noticing 
them. They are almost exclusively visited by one of the Hyme- 
noptera, viz., Andrena florea, and it can find them in the most out- 
of-the-way places. This can hardly be accounted for except by 
supposing that the scent of bryony flowers 1s perceived by these 
particular bees and not by other insects.’’ He admits these con- 
clusions must be accepted with discretion. Andrena florea gets 
its pollen exclusively from staminate plants of bryony. How 
much better do we understand the case if we admit that the 
scent of the flowers is perceived by the bee? Tne mud-dauber 
makes its nests of mud and fills them with flower-spiders, which 
are so near like the color of the flowers which they frequent that 
they are enabled to capture their prey by lying in wait. Do we 
explain the case if we say that Pelopceus perceives the scent of 
mud and Thomisidz ? 
As for out-of-the-way places, my observations indicate that, 
as a rule, oligotropic bees nest in the neighborhood where their 
food plants occur, and that, when the brood emerges next year, 
it finds the flowers in bloom, and that near by. 
Asa typical case of an oligotropic bee, Emphor bombiformis 
may be mentioned. Both sexes occur in abundance on flowers 
of Hibiscus lasiocarpus, the female collecting the pollen, the males 
often spending the night in the flowers. The bees do not occur 
“xcept when the Hibiscus is in bloom. Within several yards of 
the Hibiscus I have seen the female making nests in a dry bank, 
oe ing water to soften the earth she was excavating. The bees 
coming out next year find the Hibiscus in bloom near by. The 
Only visits to other flowers I have seen the bees make were to 
