sentinel being off duty. In about five minutes' time it came out again
and flew away unmolested. I concluded from this that humble-bees, like
their relations of the hive, occasionally plunder each other's sweets.
On another occasion I found a black bee dead at the entrance of the
yellow bees' nest; doubtless this individual had been caught in the act
of stealing honey, and, after it had been stung to death, it had been
dragged out and left there as a warning to others with like felonious
intentions.

There is one striking difference between the two species. The yellow bee
is inodorous; the black bee, when angry and attacking, emits an
exceedingly powerful odour: curiously enough, this smell is identical in
character with that made when angry by all the wasps of the South
American genus Pepris--dark blue wasps with red wings. This odour at
first produces a stinging sensation on the nerve of smell, but when
inhaled in large measure becomes very nauseating. On one occasion, while
I was opening a nest, several of the bees buzzing round my head and
thrusting their stings through the veil I wore for protection, gave out
so pungent a smell that I found it unendurable, and was compelled to
retreat.

It seems strange that a species armed with a venomous sting and
possessing the fierce courage of the humble-bee should also have this
repulsive odour for a protection. It is, in fact, as incongruous as it
would be were our soldiers provided with guns and swords first, and
after with phials of assafoatida to be uncorked in the face of an enemy.

Why, or how, animals came to be possessed of the power of emitting
pestiferous odours is a mystery; we only see that natural selection has,
in some mstances, chiefly among insects, taken advantage of it to