There is but little tendency towards brilliant coloration amongst our
native aculeates. No doubt our comparatively high latitude accounts for
this to some extent, as also the fact that the aculeates do not, as a rule,
elsewhere assume great brilliancy. Even in the tropics and other warm
regions, where bright green, blue or coppery coloured species occur, they
are comparatively few in number. In this country metallic colours are to be
found in less than a dozen species, and in most of these it exists only as
a tinge. Amongst our ants and wasps it does not exist at all, unless the
slight bronziness of the typical form of _Formica fusca_ be so considered.
The fossors can exhibit only a bluish tint in _Mutilla Europaea_ (pl. A, 4,
5), and a slight bronzy tinge in two of quite the smallest species,
_Miscophus maritimus_ and the [male] of _Crabro albilabris_. The bees can
do a little better; five species of _Halictus_ have a distinctly {120}
bronzy head and thorax, and in three the bronzy colour extends to the
abdomen; there is also another with a very dull green tinge on the thorax;
besides these there is a little bright blue bee, _Ceratina_ (unfortunately
a great rarity in this country) and two or three species of _Osmia_,
showing more or less tendency to bronziness, and one which is distinctly
bluish; but, considering our indigenous species number nearly 400, this is
a very small, and compared with other countries I should think an
abnormally small, proportion.
Species with bodies banded like a wasp's are much more abundant--no less
than eighty of our native kinds having this style of coloration. The bands
may be reduced to lateral spots, but such cases, I think, are only
modifications of the banded scheme.
Black species with a more or less pronounced red band across the body
number about seventy, and a general testaceous or yellowish colour occurs
in a few ants, but not elsewhere among the British aculeates. Nearly all
the rest are black or dark brown so far as the actual surface of the body
is concerned; but amongst the bees {121} there is often a dense clothing of
coloured hairs sometimes so dense that the surface of the body may be
rendered invisible. These coloured hairs may be distributed into brilliant
bands, as in the humble bees, or they may be uniformly black, as in some of
their varieties and in the females of the spring species of _Anthophora_
(pl. D, 25), or entirely red as in _Andrena fulva_ (pl. B, 16), or black on
the thorax and red on the abdomen as in _Osmia bicolor_ (pl. D, 28), or
vice versa as in _Andrena thoracica_, etc., but the most usual condition is
that where the hairs form more or less pale bands along the joints of the
segments, either immediately above or below them or both; sometimes these
bands are very obscurely indicated, and visible only in certain positions.
At others they are vividly white; to a certain extent this banded condition
recalls the waspy coloration. The hairs, however, of the bands are rarely
yellow, but as a rule greyish or white, or of a grade of colour slightly
paler than those of the disc. There are some rather interesting points
which arise out of this rough analysis. Among the bees, all the species
which have a waspy coloration are cuckoos, with only one exception
(_Anthidium_) {122} (pl. D, 27), as are also nearly all those which have
red bands. With the exception of the males of three species of _Halictus_,
and both sexes of three or four species of _Andrena_, all the red-banded
forms belong to the genus _Sphecodes_ (pl. B, 11), which is a cuckoo genus.
The red coloration occurs chiefly on nearly naked surfaces; this is
specially noticeable in those bees which have two varieties, such as
_Andrena rosae_, one dull coloured and the other red-banded: in these cases
the dull form is hairy and the red nearly naked. The greatest proportionate
number of banded species occurs amongst the fossors, and these are seldom
clothed with hairs to any extent. These bands seem to me probably to depend
a good deal on retarded development. Dark and hairy bands, both as a rule,
follow the joints of the segments, as stated above. I only say as a rule,
as there are many where the banding does not follow this principle, but in
far the larger majority the bands, whether of dark colour or hairs, are
apical. As the segments overlap at the joints it is evident that their
discs would tend to mature more rapidly than the overlapping bases and
apices, {123} and the longer period spent in hardening and drying of the
overlapping parts would favour the development of dark pigment and of
hairs. Many species have the extreme apices of the segments pale, but with
the apical integument so very thin, often looking nearly transparent and
membranous, that its development would be very rapid. Again, in the case of
red coloration, the red generally occurs on the discs of the segments, the
apices and sides often being dark, and in cases where in one species both
black and banded forms occur, with intermediate varieties, the last remnant
of red colour is generally situated in the centre of the segment. By far
the gayest effect is displayed by our humble bees, and, but for them and a
few of the species of _Andrena_ and the wasp-coloured species, our
aculeates would be a very sombre lot.
* * * * *
{124}