and the imaging is easy...Flies are flyin' and bees are a buzzin'...Oh,
the Velvia's rich and your images are good lookin'...So hush,
little photographer...Go out and give it a try!"
George and Ira Gerschwin I'm not! Invariably the question will
be asked about a flying critter, "Is this a fly or a bee?"
Nature, in all her glory, has seen fit to create a myriad of insects
that mimic one and another, especially when it comes to flies
and bees and wasps. By now, we are all familiar with syrphid flies
that look like yellow jacket wasps and robber flies that mimic
bumble bees. But, how can we be sure?
follows is a discussion of the major characteristics that will
help our members differentiate between flies, bees, wasps, and
flying ants. As always, there will be exceptions to some of the
listed characteristics but, the characteristics taken as a whole
for the particular orders, will be accurate. (Hint: Never
base an ID on a single characteristic. For example, mayflies
have only 2 wings, too.) Fly characteristics will appear in the
left column and bee/wasp/ant characteristics will appear in the
Syrphid Fly Wing
Bumble Bee Wing
(Flies)...Diptera (di--two; ptera--wing) literally
means "2 wings". This is, indeed, the easiest characteristic
to use to differentiate a fly from a bee, wasp, or flying
ant. What would normally be a hind wing becomes a reduced
appendage called a "haltere". The halteres do not
resemble a typical wing. The halteres are instrumental in
the equilibrium of the fly while flying. Don't mistake the
"calypters" for halteres. The calypter is a part
of the front wing.
Hymenoptera (Bees, Wasps, Ants)...Hymenoptera (hymen--union;
ptera--wing) refers to the union of the front wing
with the hind wing in flight. The leading edges of the hind
wings have hooks, "hamuli", that catch the trailing
edges of the front wings. The major characteristic to note,
here, is that bees/wasps/flying ants have 4 wings. The hind
wing is smaller than the front wing and can be greatly reduced
in size. However reduced in size, the hind wing will always
look like a wing.
Calliphorid Fly Head
Golden Wasp Head
examination of a fly's head will reveal several identifying
characteristics. Typically, a fly's antennae are short and
club-like. There are exceptions in which the antennae may
be long, and many segmented but those species are fairly
rare. Only flies have "aristae" (bristles) that
arise from the antennae. Some flies, such as mosquitos and
gnats, can have very long, bristly antennae that make the
antennae look like miniature ostrich plumes. These antennae
are said to be "plumose".
have true bristles on their heads and bodies. Bristles are
stout, tapering hairs. Flies, bees, and wasps can have fine,
short hairs covering their heads and bodies but, between
Diptera and Hymenoptera, only flies have true bristles.
eyes of a fly pretty much dominates the head. The fly's
eyes are more hemispherical in shape than a wasp's eyes
or a bee's eyes. Some flies have such large, domed eyes
that the eyes will touch, or nearly touch, at the top of
the head. Of course, as stated before, there may be exceptions.
flies have a proboscis (not illustrated) which they can
extend. The proboscis is formed by the fusion of mouthparts
and also contain a tongue. Flies do not have jaws. The "bite"
of a fly is actually the proboscis piercing your skin.
chosen a golden wasp head for a typical Hymenoptera head.
It should be readily apparent that a bee's, wasp's, or ant's
head lacks bristles. Hymenoptera may be covered head to
anus with fine, short hairs (see honey bee leg, below) but
Hymenoptera will lack true bristles on the head. Ants may
have hairs in thick or thin numbers which superficially
look like bristles but they are, indeed, hairs. Also, the
antenna can be quite variable. The antennae are generally
multi-segmented and longer than those found on flies. Many
parasitic wasps may have thin, multi-segmented antennae
as long as their bodies.
flies, many Hymenoptera have jaws and can deliver a nasty
bite! The jaws move side-to-side. Most wasps, carpenter
bees, and leaf-cutting bees have jaws that cover a proboscis
(not illustrated) with tongue. Nectar gathering Hymenopters,
honey bees and bumble bees, for example, do not have jaws
but have a protrusible proboscis. The proboscis is long
enough to reach nectar at the bottoms of deep flowers.
species of Hymenoptera the eyes do not dominate the head.
Rather than being dome-like, typical Hymenoptera eyes are
somewhat compressed laterally. Rarely are the eyes of a
bee or wasp large enough to meet on the head. Ants, on the
other hand, have greatly reduced eyes.
Honey Bee Hind Leg
third characteristic to observe are the insect's feet and
legs. For the majority of fly species we normally encounter
the feet will have pads (pulvilli) that allow flies to crawl
on smooth objects in addition to tarsal claws. Between the
tarsal claws there may be an "empodium". The empodium
may be a single bristle or may look like another pulvilli.
Not all flies have these but most do. Wasps, bees, and ants
will not have these pads.
wasp, and ant legs will never have an empodium and pulvilli.
Very seldom will there be hairs attached between the tarsal
claws. There may be hairs, however, that extend from the last
tarsal segment. Flies will never have pollen baskets. Some
flower-feeding flies may become coated with pollen but flies
lack the mechanism for compacting pollen into a tight package.
a little test...You photograph an insect with 2 short antennae,
large hemispherical eyes, 2 wings, and 2 long, fine tails?
A fly, right? Wrong! A mayfly. Flies will have halteres and
never have tails! OK, maybe that wasn't fair but always look
the insect over carefully to make sure you see all of the
key characteristics before committing to an identification.
With the key characteristics, outlined above, you should not
have any difficulty separating the majority of the flies from
bees, wasps, and ants.
Thomas L Webster 2005. All rights reserved.