This is not an easy question to answer. We cannot make hard and fast
definitions which will determine exactly what belongs to this group and
what to that; there are always some intermediate forms which present
themselves and make our classification unsatisfactory, but, I think, for
all purposes of practical observation in the field we may say that if we
find a creature with four membranous wings, burrowing in the ground or
making a nest in any way, it is an aculeate or stinger. Also, that if we
find a hairy-bodied insect with four clear wings collecting pollen or
sucking nectar from a flower it is a bee. There are, of course, characters
by which the stinging groups can be known almost for certain, but there is
no single one which can be given to recognize them by. {93} They are known
by a combination of many, and these are frequently small structural details
which do not appeal to the field observer; in fact, which are unappreciable
except under magnification. One of the chief difficulties experienced by an
observer who is not versed in classification is to avoid being deceived by
various flies, which in many cases greatly resemble bees, and especially
wasps or the wasp-like fossors. They may mostly be known by their flight,
and, when they settle, by their behaviour. A fly is more sudden in its
movements--those wasp-like flies, for instance, which poise themselves in
the air and appear quite stationary but dart off in a second when
approached, betray themselves at once by their alertness. _Anthophora_ and
_Saropoda_ poise in the air and dart somewhat after the same fashion, but
they never remain poised for long, and do not get away from their position
so rapidly. Also, a fly when it settles remains quiet, whereas an aculeate
if in a flower sets to work collecting pollen, or if basking in the sun on
a leaf rarely rests for many seconds without moving in some way. On a
flower, if an insect is seen quietly sitting with its head away from the
centre of the {94} flower, it is almost certain to be a fly. Most of the
little bees (_Halicti_) which visit dandelions and such like "composites"
fly in to them with some rapidity, attack them sideways, and move round the
"flower", no doubt getting pollen from each floret in succession and with a
businesslike action about it all, which is very different from the
behaviour of any fly. The flies which really closely resemble bees in their
flight are those which lay their eggs in the burrows of various bees and
sandwasps. They are really deceptive. Last summer on the sandhills at
Southbourne, near Bournemouth, I again and again was deceived by a small
fly with a red belt across its body, thinking it was a red-bodied sandwasp.
These it really only resembles on the wing. After having been taken in once
or twice one felt ashamed of oneself for not recognizing it. The flies also
which associate with the humble bees are often coloured very much like
them, and could easily be mistaken for small specimens of the bees were it
not for their behaviour and wings, which show a dark spot on the upper
margin, not existing in the wing of the bee.
* * * * *
{95}