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Life-history of Melittobia acasta 
I have experimented with the following hosts: 
Osmia rufa 
Megachile spp. 
Odynerus spinipes 
,, antilope 
„ callosus 
Vespa sp. 
Trypoxylon figulus 
Crabro sp. 
Chrysis ignita 
Ichneumonid parasite of larvae of Hypera variabilis 
Paralyzed larvae of Hypera variabilis 
„ Tineid caterpillars 
„ spiders 
Donacia pupae 
Calliphora, Musca, etc., puparia 
Urophora solstitialis (Muscid) pupae 
From cells of 
solitary wasps 
Psen sp. 
In every case, excepting the paralyzed spiders and larvae from the cells 
of solitary wasps, I have succeeded in rearing the parasite on these hosts but, 
as will be seen later, in one case, that of Osmia rufa , the food seemed very 
unsatisfactory ( v. Chap. XI). 
III. Male and Female Characters. 
The male and female imagines are very different from one another. The 
former (Plate XXVI, fig. 1) is of a dark brown colour, even reddish, with minute 
wings quite useless for flight. The anterior pair, which are the larger, are only 
about one-third the length of the insect and, when lying at rest on the dorsum, 
only reach just beyond the first visible abdominal segment, the posterior pair 
not extending more than two-thirds of the way across this segment. 
The head bears on each side, instead of the usual compound eyes, a single 
ocellus and there are also three ocelli in a group in the usual position on the 
vertex. 
The antennae are very peculiar. They consist of what are apparently eight 
segments but the apical one is two or three segments compressed to form a 
club. The scape consists of one very large segment which forms about half 
the total length of the antenna. This large segment is broad and triangular 
in shape, attached to the head by one angle, the flagellum being attached to 
it at one of the others, the inner one when the antenna is viewed from above. 
On the under side of the scape at its distal end and between the two angles 
is a hollow space (Plate XXVI, fig. 1 a, b). 
The female (Plate XXVI, fig. 2) is darker in appearance, being usually pitchy 
brown, has compound eyes and the normal chalcid elbowed antennae. The 
wings, which overlap when at rest, extend almost to or slightly beyond the 
apex of the abdomen, this depending upon whether the latter is full of eggs 
or otherwise. 
The only published figures, so far as I can find, are those of Graham Smith 
(1915-16 and 1918-19) who illustrates male and female in both his papers, but 
as the figures in the two papers are so different and as, in my opinion, they 
do not give a correct idea of the insect, I have made drawings for this paper. 
Waterston (1917) gives figures of certain parts of the adult insects such as 
the male antenna and the metasternum and first abdominal segment on a 
larger scale than in my drawings. 
