Digger Bees
Order:
Hymenoptera
Family: Anthophoridae
Subfamily:
Anthophorinae
Digger bees, also known as flower-loving
bees, are distributed throughout most of North America.
These robust bees usually go unnoticed as they feed, collecting
nectar and pollen from a wide variety of flowers in meadows and gardens.
When they begin to build their numerous solitary nests in the same
area, however, they become a nuisance to property owners.
Biology and Habitat
Densely covered by yellow and black hairs, digger bees closely resemble their cousin, the carpenter bee. This subfamily has unique characteristics. It has short yellow hairs on the head, thorax and the first abdominal segment. Its legs are covered with short black hairs, and the hind tibia has apical spurs (pollen brushes). In addition, the digger bee has a narrow gena (cheek) and a tergal (dorsal-side) plate on the last abdominal segment. The wings are clear, but somewhat smoky at the tip. The forewings have a small spot on the leading edge, whereas the hind wings have a jugal lobe (a lobe at the base of the wing on the posterior side).
Although solitary bees,
digger bees often build nests in a common area.
Sand and clay banks lacking ground cover are most attractive to
these anthrophorids. The
entrance of each individual nest is hidden by a down-slanted chimney composed
of mud. Inner-branching tunnels extend from this chimney and are also
lined with mud. These tunnels
are partitioned into brood cells, each containing an egg. The adult bee places honey and pollen within each cell to provide
nourishment for the developing larva after egg hatch. The larva will overwinter in its brood cell, and after pupation,
the adult emerges in late spring.
Control
Since the digger bee may closely resemble the carpenter bee and the bumblebee at a first glance, closer examination is often needed before prescribing a control method. These bees do not cause structural damage. Therefore, if an assemblage of adult bees is seen building their nests on a distant slope away from a structure, an informative explanation of their behavior to the property owner may be all that is needed. Planting ground cover on embankments may discourage the bees from selecting these sites for nest-building the following year.
If the bees are a nuisance near a structure, several treatment options are available. For a large site, use a powder-sprayer with an appropriately labeled insecticide, while a back-pack sprayer may provide enough coverage for a smaller area. Avoid runoff by using low pressure to ensure that the insecticide penetrates into the brood cells.
Consider the formulation
when selecting an insecticide. Wettable
powders and microencapsulated formulations are probably the best choice.
Dusts can be effective if applications can be applied directly
into nest openings.
(Courtesy of the National Pest Control Association.)