with the bottom of the
tunnel, and then five males.

2. A series of nine: three females first, then six males.

3. A series of eight: five females followed by three males.

4. A series of eight: seven females followed by one male.

5. A series of eight: one female followed by seven males.

6. A series of seven: six females followed by one male.

The first series might very well be complete. The second and fifth
appear to be the end of layings, of which the beginning has taken place
elsewhere, in another bramble-stump. The males predominate and finish
off the series. Nos. 3, 4 and 6, on the other hand, look like the
beginnings of layings: the females predominate and are at the head of
the series. Even if these interpretations should be open to doubt, one
result at least is certain: with O. detrita, the laying is divided into
two groups, with no intermingling of the sexes; the first group laid
yields nothing but females, the second, or more recent, yields nothing
but males.

What was only a sort of attempt with the Three-pronged Osmia--who, it is
true, begins with females and ends with males, but muddles up the order
and mixes the two sexes anyhow between the extreme points--becomes a
regular law with her kinswoman. The mother occupies herself at the start
with the stronger sex, the more necessary, the better-gifted, the female
sex, to which she devotes the first flush of her laying and the fullness
of her vigour; later, when she is perhaps already at the end of her
strength, she bestows what remains of her maternal solicitude upon the
weaker sex, the less-gifted, almost negligible male sex.

O. parvula, of whom I unfortunately possess but one series, repeats
what the previous witness has just shown us. This series, one of nine
cocoons, comprises five females followed by four males, without any
mixing of the sexes.

Next to these disgorgers of honey and gleaners of pollen-dust, it would
be well to consult other Hymenoptera, Wasps who devote themselves to the
chase and pile their cells one after the other, in a row, showing
the relative age of the cocoons. The brambles house several of these:
Solenius vagus, who stores up Flies; Psen atratus, who provides her
grubs with a heap of Plant-lice; Trypoxylon figulus, who feeds them with
Spiders.

Solenius vagus digs her gallery in a bramble-stick that is lopped short,
but still fresh and green. The house of this Fly-huntress, therefore,
suffers from damp, as the sap