Kronfeld has shown that aconites are dependent for this on the visits of a Bombus and cannot exist outside the area where it occurs.
The " tongue," for example, is short and obtuse or emarginate in Colletes and Prosopis, while in all other bees it is pointed at the tip. But in Andrena and its allies it is comparatively short, while in the higher genera, such as A pis and Bombus, it is elongate and flexible, forming a most elaborate and perfect organ for taking liquid food.
Among the humble-bees (Bombus) the workers help the queen, who takes her share in the duties of the nest; the distinction between queen and workers is therefore less absolute than in the hive-bees (Apis), whose queen, relieved of all nursing and building cares by the workers, devotes her whole energies b FIG.
The tongue is bifid at the tip in a few genera; usually it is pointed and varies greatly in length, being comparatively short in Andrena, long in the humble-bees(Bombus), and longest in Euglossa, a tropical American genus of solitary bees.
The leaf-cutter bees (Megachile) - which differ from Andrena and Halictus and agree with Osmia, Apis and Bombus in having elongate tongues - cut neat circular disks from leaves, using them for lining the cells of their underground nests.
In our well-known hive-bee (Apis) and humble-bees (Bombus) the wax glands are ventral FIG.
The colonies of Bombus illustrate the rise of the inquiline habit.
Sladen states that a queen belonging to the virginalis form of Bombus terrestris often invades a nest belonging to the lucorum form, kills the rightful queen, andtakespossession of the nest, getting the lucorum workers to rear her young.
Von Jhering, who points out that their wax glands are dorsal in position, not ventral as in Bombus and Apis.