[ APPS ]
Columbia University, University of
Maryland, and Smithsonian Institution
What it can do:
This app uses visual recognition
technology (adapted from facial
recognition software) that lets users
identify trees in the northeastern U.S.
and eastern Canada by snapping photos
of their leaves. In order to work, a single
leaf must be photographed on a white
background and an Internet connection is
required as each image is automatically
sent to a server for processing. Some
user reviews note that the photo
recognition technology does not always
provide accurate results; even so, the app
includes high-resolution images of the
flowers, fruits, petioles, seeds, and bark
of trees in its database, so you can do
comparisons the old-fashioned way, too.
How to Get it:
Leafsnap is currently available for
iPhones and iPads on the App Store; an
Android version is under development.
[ THE OUTSIDE STORY ]
Bee Mimics: Their Buzz
is Worse Than Their Sting
A while back I had a few hives of honey bees parked at a beef farm down the road, tucked up
against a stone wall just outside a pasture. One day the owner called to say that my bees had
invaded a building in a barn complex and were laying eggs in manure puddles.
I went down to check it out, and the building did have a lot of buzzing insects butting their heads
against the windows. I looked closer. They looked like honey bees, but...not quite. And there were
weird larvae wriggling in water seeping from manure.
I assured my neighbors that they weren’t going to get stung by those “bees,” then hot-footed
it home to do some research. It didn’t take long to identify them as drone flies, Eristalis tenax, a
member of the family Syrphidae, the hoverflies. According to the National Audubon Society’s Field Guide
to North American Insects and Spiders, while adult drone flies feed on nectar and pollen, their larvae
(called rat-tailed maggots because of the snorkel-like breathing tubes at the tips of their abdomens)
are famous for being found on carrion and open latrines. In fact, this fly is likely the source of the myth
that honey bees develop in dead animals, a story that goes back to the Old Testament.
The drone fly is a common bee mimic. But it’s not the only one. There are hundreds of species
of hoverflies, and most of them mimic bees of one kind or another, said entomologist Jason
Dombroskie, the manager of the Cornell University Insect Collection and coordinator of the school’s
Insect Diagnostic Lab.
“The mimicry can be quite impressive,” he noted. “If you look at popular media articles on any-
thing to do with bees, there’s a good chance that that stock photo they choose will not be of a bee.
There’s a good chance it will be a fly.”
Bee and wasp mimics are exhibiting Batesian mimicry, named after English naturalist Henry
Walter Bates. They’ve evolved colors and behaviors that mimic those of insects with a reputation of
stinging if messed with – but not the sting itself. Most commonly they’ve evolved some variation of
yellow and black banding that says STINGING INSECT! “We associate yellow and black with danger,
even though most bees are not aggressive,” said Dombroskie.
It seems that almost every species of wasp or bee has its Batesian imitators. In addition to flies there
are beetles and moths that resemble bees and wasps. Most of these mimics are harmless, Dombroskie
says. “They can’t sting. They will act like they can. If you grab them they’ll buzz and be quite intimidating.”
While mimics can fool you at first glance, there are ways to tell the real from the pretend. In the
case of flies, they have two wings to a bee’s four. And while a bee’s antennae are crooked in an elbow
shape, flies have short, or very fine, antennae. Behavior provides clues as well. Bees, hard work-ers that they are, move purposefully from flower to flower, while hoverflies, well, hover, and move
erratically, zipping here and there. In the case of beetles that mimic bees, you should be able to pick
out the beetle’s elytra, or the hard shell of the overwing. And in the case of bee-mimicking moths,
including many of the hawk moths, their overlong proboscis is a clue.
While the mimics are frauds as stinging insects, when it comes to pollination, most are the real thing.
Hoverflies, like my friends’ drone flies, are considered to be important pollinators, though exactly how
important is not really known. Pollination research has been concentrated on bees. Dombroskie noted
that flies may not be as efficient at pollination since they tend to be generalists, visiting a variety of
flowers, while bees tend to concentrate on one type at a time. But they’re still out there helping plants
spread their genes.
The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is sponsored by the
Wellborn Ecology Fund of New Hampshire Charitable Foundation: firstname.lastname@example.org