Pollen Baskets (Corbicula)

Common Eastern Bumble Bee - Bombus impatiens

(Photo:  Marvin Smith on 11/8/09)

Most everyone knows that bees visit flowers and collect nectar. Humans value the nectar product and call it honey. Bees also collect pollen. To the bee, pollen is as important as nectar. Pollen is the primary food for developing bee larvae.

Female bees (queens and workers) in family Apidae (honey bees, carpenter bees, bumblebees and several lesser known groups) have specialized structures called pollen baskets (corbicula) used for temporarily storing collected pollen so it can be transported back to the nest/colony. The pollen basket is a smooth, concave structure surrounded by long, stiff hairs located on the tibia of the bee's two rear legs. As the bee visits flowers, she accumulates pollen all over her body. She uses her legs to aggregate the pollen and transfer it to her pollen basket. It may look as if a bee simply has hairy legs, but some of those hairs (setae) are actually combs and brushes used for transferring pollen. The pollen is combed, pressed, compacted, and transferred to her pollen basket. Honey and/or nectar is used to moisten the dry pollen so it will stay in place.

Bumblebee with loaded pollen basket.

(Photo:  Beatriz Moisset via Wikimedia)

While most all bees collect pollen, not all bees have pollen baskets. Many have scopa, a general term referring to a number of different pollen-carrying modifications on the body of a bee. In most bees, the scopa is simply a particularly dense mass of elongated, often branched, hairs (or setae) on the hind leg.

Halictid bee, scopa loaded with pollen.

(Photo:  Beatriz Moisset via Wikimedia )

The bumblebee in the photo at the top of the page is a Common Eastern Bumble Bee (Bombus impatiens), probably the most often encountered bumble bee in eastern North America. It has an unusually long flight season and thrives across a wide range of habitats and climates ranging from the cold temperate zone (e.g., Minnesota) to the warm subtropics (south Florida). B. impatiens can be found in rural, suburban and urban environments. There are isolated pockets of Common Eastern Bumble Bees outside of it's normal range -- like California -- because it escapes from commercial greenhouses where it is used for pollination. The bee has no pollen because this photo was taken in early November when pollen sources were few and far between. She was lucky to find a few scraggly zinnias still blooming in our garden.

Sources and links:
Bombus impatiens on BugGuide
Pollen Basket on Wikipedia
Scopa on Wikipedia
Bumblebee legs on Bumblebee.org

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

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Pollen Baskets (Corbicula)

Tachinid Fly (Genus Peleteria)

In general, most tachinid flies are relatively large and bristly.  They often mimic wasp or bees.













Adult tachinids feed on pollen and nectar.  Larvae are parasites, preying on other insects -- often caterpillars.  Most tachinids deposit their eggs directly on the body of their host, and it is not uncommon to see caterpillars with several tachinid eggs on them. Upon hatching the larva usually burrows into its host and feeds internally. When fully developed it leaves the host and pupates nearby.   Larvae of Genus Peleteria prey Lepidoptera (butterflies and moths).








There are 1,345 species in 303 genera of tachinid flies in North America.  They can be found practically anywhere and everywhere. Tachinids are often abundant on sunny hilltops looking for mates.









Information source:  BugGuide

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Tachinid Fly (Genus Peleteria)

Digger Bee

Digger Bee - Svastra obliqua

The common name digger bee is based on the fact that most of the bees in this tribe dig holes in the ground for their nests. Other digger bees nest in wood and some are parasites of other bees. Parasitic digger bees do not construct nests.

Digger bees are also sometimes called longhorned bees due to the especially long antennae of the males. The bee in the photo above is a female.

The velvety fur of digger bees is one of the things that makes them excellent pollinators. All that hair collects a lot of pollen as they move from flower to flower. This particular bee is relatively free of pollen because she had just cleaned herself. When I first noticed her, she was hanging off the tip end of a flower petal by her mandibles and scraping the accumulated pollen off her legs.

Front view



Cleaning off pollen.

Digger Bee

Sinuous Bee Fly

Sinuous Bee Fly (Hemipenthes sinuosa)

One of the many larger bee flies that frequent flowers and eat nectar (and maybe pollen). Many of the bee flies have a long proboscis but this species does not.

"Sinuous" is based in Latin and refers to the wavy, undulating border formed by the black area on the fly's wings.

Sources:
BugGuide: Sinuous Bee Fly
BugGuide: Family Bombyliidae

Sinuous Bee Fly