SOLITARY BEES AND WASPS OF ESSEX. 85
Caelioxys acuminata (Essex Nat., xxi., p. 29). In this instance
the "cuckoo" bee entered the nest under observation and
succeeded in laying its egg in the absence of the host bee ; the
latter returned as the "cuckoo" was leaving and a severe tussle
ensued, but neither combatant was any the worse apparently.
The noteworthy feature of this observation is that the bee
afterwards chewed up the whole of the cell, and its contents,
including, presumably, its own egg as well as that of the Caelioxys !
Instances are given by Shuckard (British Bees) of fierce contests
between Anthophora (host) and Melecta (cuckoo) females on such
occasions, but other writers appear to think that some other
interpretation should be put on these occurrences, which have
not been frequently observed. In the case of the Humble-
bees, however, the "cuckoo" queens (Psithyrus) invariably
kill the host queens and usurp their position in the nest. The
"cuckoo" larvae of the "solitary" Aculeate groups devour the
food of the host larva, leaving the latter to starve to death ; the
cuckoo larvae of the Chrysid group, on the other hand, devour the
host larva itself when it is full fed.
Mention of the Chrysids reminds us that besides the traitors
in their camps, as the "cuckoo" bees may be called, bees and
wasps are subject to being imposed upon by "cuckoo" species
of other groups of the Hymenoptera and also of other orders of
insects. Of these the Chrysidoidea have already been mentioned,
and they are all "cuckoos" in the nests of various other insects ;
there are also the Braconids, Chalcids, Proctotrypids and
Evaniids, as well as some of the true ichneumonflies (Ichneu-
monidae) of the great section, Ichneumonoidea, of the Hymenop-
tera. The Diptera are represented by Bombylius (Humble-bee
flies) and Miltogramma. The Coleopterous "cuckoo" is Meloe
proscarabaeus, one of the oil-beetles. The Dermaptera are
amply represented by the common earwig, which works much
havoc amongst the burrowing species, devouring their larvae
and their stores of food. It is among the Strepsiptera, however,
that we find the most dreadful examples of all the "cuckoos"
in the genera Stylops and Halictoxenus. The former genus afflicts
Andrena mainly ; the latter, Halictus. In the case of Stylops
the female does not come forth from the body of the host bee,
but the young Stylops larvae emerge first from their mother's
body and then find their way through that of the bee, over