BEES, WASPS, ANTS, ETC. 541 



pollen. The cells of Xylocopa virginica are about seven tenths of an inch in length, 

 and are separated from each other by partitions which are similarly constructed by the 

 other species. Each partition seems to be made from a single flattened band of saw- 

 dust and fine chips, agglutinated together and rolled up into a band about four layers 

 deep. The side forming the bottom of the cell is concave and smooth, while the other 

 side is flat and rough. 



Last and highest in the order Hymenoptera comes the sub-family Socialinise, or, 

 social bees. The social bees are readily distinguishable from the other members of 

 the family Apidse by several striking peculiarities. As with the social wasps, each 

 species is composed of three classes of individuals, males, females, and drones, or 

 workers. They live gregariously in larger or smaller communities. They have the 

 power of secreting wax, from which their cells are made, and the larvae are fed from 

 time to time by the workers. The outer side of the dilated posterior tibisB is smooth, 

 and in the workers is hollowed into a shining plate for carrying pollen, which is col- 

 lected by means of the pollen-brushes on the basal joint of the hind tarsi. The 

 maxillary palpi are very small. As a general thing the body is covered with hair, 

 though some Brazilian species of the genus Exiglossa are naked. 



The genus JBombus includes the so-called " humble " or " bumble " bees. In this 

 genus the body is oblong and densely pubescent, mandibles stout, grooved exteriorly 

 towards the rounded apex, labial palpi four-jointed, labium long, pubescent, maxillary 

 palpi two-jointed, fore wings with one marginal and three sub-marginal cells. With 

 the males the mandibles have a dense fringe of curled hair on their inferior margins. 

 The genus has an extensive geographical range, and is found all over the world, with 

 the exception of Australia and New Zealand. Into the latter countries it has been 

 introduced, to aid in the fertilization of the clover crop. Over sixty species have been 

 described from North America. The species are very difiicult to separate, owing, prin- 

 cipally, to the great colorational variation in the males. The economy of the genus 

 has long been studied, and has been quite fully detailed by several authors. The 

 females or queens alone hibernate. During the winter months they may be found, 

 always singly, hidden away in decayed trunks of tree, under fodder stacks, under 

 leaves, or moss, or in other sheltered and dry situations. That they sometimes winter 

 in the old nests is both stated and disputed. In the spring each female becomes the 

 foundress of a new colony. She selects some spot, under a stump or sod, or often in 

 the abandoned nest of a field mouse, and immediately collects a mass of pollen which 

 she mixes with honey, and in which she deposits a small number of eggs. The eggs, 

 according to F. W. Putnam, are laid in contact with one another, in one cavity of the 

 pollen mass, with which they are slightly covered. The larvae, hatching, begin feed- 

 ing on the pollen, and push out in independent directions, increasing in size, and mak- 

 ing large cavities in the mass. On reaching full size, each spins a silken covering, 

 which is thickened by a wall of wax added by the adult bees, so that a cell is formed 

 in which the larva transforms to a pupa. The development is very irregular, and a 

 nest examined at almost any time during the summer will be found to contain the 

 insects in almost all stages of growth. The first brood is composed of workers, and 

 after their appearance the queen leaves the work of provisioning to them and devotes 

 herself almost exclusively to homo duties. The workers are assiduous in their labor 

 of collecting and storing up pollen, and in their care of the young. They assist the 

 newly-formed bees to emerge from their cocoons, helping them to cut and remove the 

 lid, and pulling them out with their mandibles. More eggs are laid and new cells are 



