128 
WILD DEES. 
June, 1889. 
attained than would be possible if it kept its wings erect. And 
it is most interesting to note that specimens caught on dry 
liill-sides, where it rests on grass heads, are more variegated 
than those caught in marshy places where rushes abound, 
just as the blossoms of grasses are more variegated than the 
blossoms of the rush. 
To return to the bees, the wasp-like colouration of many 
of the Nomadce is worthy of consideration. The number of 
insects which mimic the Vespidce is immense. Familiar 
instances are found in Diptera , Coleoptera, and Lepidoptera, and 
it is interesting that similar instances should occur amongst 
the stinging Hymenoptera. I think there are no more truly 
vespiform insects than these Nomadce, and many of the 
Fossorial Hymenoptera are also exceedingly wasp-like. 
One of the species of this genus was used by Mr. Poulton 
in his experiments (Proc. Soc. Zool., March, 1887) on the 
“ Value of Colour and Markings in Insects,” and he found it 
was untouched by any of the lizards to which it was offered. 
As the Nomadce have the power of emitting an odour, which 
is no doubt protective, this should also be taken into account 
in the experiment. 
The colours of the other species of the genus, which 
are chiefly brown and black, may also be warning ones, for 
they are very conspicuous when the insect is on the wing, 
but it is these species which are the most beautifully protected 
when at rest. 
Here then is a genus the members of which are protected 
by a scent, by protective resemblance, by warning colours, 
and by a sting ; but it is clear that insects so protected 
cannot often require to use that sting, and I feel sure that 
it is from this cause that of all our bees, or at least of those 
of equal size, the sting of the Nomadce is the least painful. 
Even if they do succeed in piercing the skin, the pain is 
exceeding slight and lasts only for a minute or two. The 
Fossor Philanthus, too, which I have mentioned as provision¬ 
ing its cells with bees, has a fierce wasp-like appearance ; 
when handled it appears to make no attempt to sting. Many 
of the larger species of Crabro also, which I have often found 
carrying off large flies to their cells, look like large-headed 
wasps, and though I have occasionally handled them I do not 
remember ever being stung by them. 
I must now pass on to another enemy by which 
Andrena is attacked, namely, the very curious genus Stylops ; 
indeed these insects are so peculiar in structure that the 
late Mr. Kirby made for them a new order, which he called 
Strepsiptera. The fore wings or wing-cases of the male are 
