266 MODERN CLASSIFICATION OF INSECTS. 
legs, it is evident that they cannot be pollinigerous, as indeed Messrs. 
Serville and St. Fargeau affirm. (ne. Méth. tom. x. p. 447.) 
The Halicti consist of some of the smallest indigenous species of bees. 
In the males, the body is cylindric, and in the females the extremity 
of the abdomen is marked with a longitudinal channel. Some of the 
species are metallic in their colours. We are indebted to M. Walck- 
enaer for a very interesting and complete account of the habits of two 
of the species of this genus, namely, the Halictus terebrator and 
4-signatus, which make their burrows in beaten tracks, depositing in 
the cells with their eggs a small ball of pollen slightly moistened with 
honey. The burrows are often to be observed in vast numbers, placed 
close together. See also Hncyclop. Méth. (tom. x. p. 407.) for further 
details of the habits of this genus. 
The species of the genus Andrena are very numerous, and make 
their appearance in the early spring and summer months: they have very 
much the appearance of hive bees (fig. 90. 1. Andrena nigro-enea ? , 
2—8s. details). They nidificate under ground in a light soil, forming 
burrows from five inches to a foot deep ; preferring a southern aspect, 
and removing the earth grain by grain. The diameter is sufficient 
only to allow the bee to enter and go out; at the foot of this burrow 
they deposit an egg, placing with it a small mass of pollen paste. 
The pollen is carried not only upon the pollen plate of the hind leg, but 
also upon the pollen brush at the base of these legs, and at the sides of 
the metathorax. When the female has completed the deposition of her 
eggs, she carefully stops the mouth of the burrow. During the progress 
of nidification she occasionally takes rest, sitting and sunning herself at 
the mouth of her cell; her partner wheeling around her in circles of 
varied diameter, with great velocity. (Réaumur, M/ém. tom.vi. mém.4.) 
The sexes of many of the species are unknown; this is even the 
case with And. fulva, the most beautiful and by no means a rare 
species, and of which the females alone are known. They frequent 
the blossoms of the gooseberry. 
These insects are subject to the attacks of various enemies; amongst 
these, the most striking are the species of Stylops, and the curious 
little insect which has been regarded as the larva of the Meloe. 
Dr. Klug has likewise published an account of another parasite * 
upon Andrena in Der Gesellschaft Naturforschen der Freunde zu 
Berlin Magazin, vol. iv. 
* Braula cxea (Nitzsch) is another singular parasitic genus found upon bees. 
