FLOWERS AND INSECTS. XIX. 
CHARLES ROBERTSON. 
1. Comparison of the genera of bees observed in Low Germany 
and in Illinois, with the number of species of each and their flower 
visits—The results credited to Miiller are taken from the Fertil- 
zation of Flowers. They are based on observations made by 
Herr Borgstette at Teklenburg, in the north of Westphalia, and 
by Miiller at Lippstadt and in Sauerland, in the central and 
southern parts of the same region, as well as observations made 
by him in Thiiringia. My results are based on observations made 
within ten miles of Carlinville. Each species of bee is credited 
with a visit for each of the species of plants on whose flowers it 
has been taken. : 
II. On the flower visits of oligotropic bees. — Those bees which 
visit a wide circle of flowers Loew* calls polytropic. On the 
other hand, the bees which restrict their visits to a few flowers 
he calls oligotropic. Cases are given by quite a number of 
authors, but, as far as I can learn, they are cited as mere curi- 
osities; and, as if to keep them more interesting by surrounding 
them with mystery, the facts which give them significance are 
omitted. The fact that a species of bee is found on the flowers 
of one or a few species of plants may only indicate that the bee 
is rare, or that the entomologist does not know where to look 
for it. Inthe economy of the host-bees (those not inquiline) 
the most important flowers are those from which the female gets 
the pollen upon which her brood is fed, and we need not trouble 
ourselves with any cases, or give special names to them, unless 
it is particularly specified that the female collects the pollen. 
The more often the female visits a flower without collecting any 
pollen, the stronger becomes the presumption that there is 
*Blumenbesuch von Insekten an Freilandpflanzen. Jahr. Bot. Gartens Berlin 
St Isea 
1899] 27 
