July, 1S89. 
WILD BEES. 
151 
There is still one species to be noticed, 0. leucomelana. 
It is a very local bee and hardly ever abundant, but I have 
met with it in South Devon, and also with the nidus. This 
is constructed in a dead bramble stem : having found a dry 
stem of suitable size, it has only to remove the pith to form 
an excellent burrow. In this it makes several cells, placing 
in each the usual little pollen mass, and forming partitions 
between them. 
Other British bees make use of bramble stems, Prosopis 
and Ceratina for example, and so do large numbers of the 
Fossorial Hymenoptera, and one cannot but wonder that a still 
larger number of bees have not thus saved themselves the 
labour of excavating harder materials. 
The genus Stelis is parasitic on Osmia ; we have but three 
British species of these parasites, all of which are rare or 
very rare. Not much is known of their habits beyond the 
fact that like other parasites they enter the burrows of the 
Osmia during her absence and deposit their egg. I have met 
with two of the species. One wet day I found a female of 
Stelis phceoptera in one of the unoccupied burrows of a colony 
of the Fossor, Crabro cephalotes, which would indicate that 
like other parasitic bees I have mentioned they do not venture 
to sleep in the burrow of their host. 
In connection with this genus may be noticed the 
brilliantly-coloured parasitic Chrysididee or Ruby wasps, for the 
OsmicB are the most liable of our bees to be attacked by them. 
They are, however, very general in their attacks, the Fossorial 
section being especially subject to them. Entering the 
burrows of the industrial bee they deposit their eggs, but, as 
one would guess from the fact of some species attacking 
either bees or the carnivorous Fossors, it is not on the food 
which is stored up that they prey, but on the larvae of their 
hosts. 
Perhaps the most noteworthy fact in the habits of the 
Ruby v^asps is the special means of protection they have 
acquired. To save themselves from the sting of the host, on 
whose young they prey, they roll themselves up into a ball, so 
that no weak spot in their armour remains open to attack, and 
many species do attack them with the greatest fury. The 
Fossor, Bernbex, is notorious in this respect. A curious fact 
is told of an assault made by one of the leaf-cutter bees on 
one of these C/mjsididce ; on its return it caught the parasite, 
and, finding it protected in all other parts, bit off its wings, 
and let it drop to the ground from its burrow, which was 
constructed in a wall. Nevertheless, when the bee had flown 
off for a fresh supply of pollen, the parasite crawled up the 
