s slenderer frame, by his long, narrow abdomen, by his red
sash. They might easily suggest two different species. The female is
a pale russet-brown; the male is black, with a few red segments to his
abdomen. Well, during the May building-operations, there is not a Bee in
sight clad in black, with a slender, red-belted abdomen; in short, not a
male.

Though the males do not come to visit the environs of the burrows, they
might be elsewhere, particularly on the flowers where the females go
plundering. I did not fail to explore the fields, insect-net in hand.
My search was invariably fruitless. On the other hand, those males,
now nowhere to be found, are plentiful later, in September, along the
borders of the paths, on the close-set flowers of the eringo.

This singular colony, reduced exclusively to mothers, made me suspect
the existence of several generations a year, whereof one at least must
possess the other sex. I continued therefore, when the building-who
was over, to keep a daily watch on the establishment of the Cylindrical
Halictus, in order to seize the favourable moment that would verify my
suspicions. For six weeks, solitude reigned above the burrows: not a
single Halictus appeared; and the path, trodden by the wayfarers, lost
its little heaps of rubbish, the only signs of the excavations. There
was nothing outside to show that the warmth down below was hatching
populous swarms.

July comes and already a few little mounds of fresh earth betoken work
going on underground in preparation for an exodus in the near future.
As the males, among the Hymenoptera, are generally further advanced than
the females and quit their natal cells earlier, it was important that I
should witness the first exits made, so as to dispel the least shadow
of a doubt. A violent exhumation would have a great advantage over the
natural exit: it would place the population of the burrows immediately
under my eyes, before the departure of either sex. In this way, nothing
could escape from me and I was dispensed from a watch which, for all its
attentiveness, was not to be relied upon absolutely. I therefore resolve
upon a reconnaissance with the spade.

I dig down to the full depth of the galleries and remove large lumps of
earth which I take in my hands and break very carefully so as to examine
all the parts that may contain cells. Halicti in the perfect state
predominate, most of them still lodged in their unbroken chambers.
Though they a