64 
INSECTS. 
Bates gives an account of the habits of a species which he noticed hovering over 
the armies of foraging ants. These ants, he says, “ are accompanied by small 
swarms of a kind of two-winged fly, the females of which have a very long 
ovipositor, and which belongs to the genus Stylogaster. These swarms hover with 
rapidly vibrating wings, at a height of a foot or less from the soil over which the 
ants are moving, and occasionally one of the flies darts with great quickness 
towards the ground. I found that they were not occupied in transfixing ants . . . 
but most probably in depositing their eggs in the soft bodies of insects which the 
ants were driving away from their hiding-places. These eggs would hatch after 
the ants had placed their booty in their hive as food for their young.” 
The family Muscidce embrjpes a large and varied assortment 
of species, of which house-flies and blow - flies are well - known 
examples. The characteristic structure of the wings may be seen by referring to 
the figure on p. 48, The proboscis is adapted for sucking, and usually ends with 
two fleshy lobes. The flagellum of the antennae is generally plumed with hairs on 
both sides, though sometimes, as in the tsetse, the hairs are restricted to one side, 
while in the spiny-flies it may be naked. The relative size of the three basal 
segments of the antennae varies in different genera, but usually, as in the blow-flies, 
the house-flies, and the tsetse, the third segment is at least three times the length 
of the second (see b in figure on p. 69, and 10 in that on p. 65). It may also be 
mentioned that the upper surface of the thorax is marked with a transverse suture, 
and that the feet are furnished with a pair of adhesive pads (11 in the figure on p. 
65). The family is divided into several subfamilies, and these may be grouped in 
two sections, based upon the presence or absence behind the wings of a membranous 
scale which, when present, covers the halteres or balancers. The subfamilies that 
possess this scale are termed the calypterate Muscidce ; while those that are with¬ 
out it are in contrast called the acalypterate Muscidce. Taking the calypterate 
Muscidce, we begin with the subfamily Muscince, of which the house-fly ( Musca 
domestica ) is the typical representative. This species may be found during 
summer in numbers in every house, crawling up the window-panes, flying in 
companies about the middle of the room, or creeping about the table in search of 
food. It is the unwelcome companion of man in every country, following him in 
his travels, taking up its residence with him wherever he may choose to settle, and 
resisting equally well the cold of northern latitudes and the heat of tropical climes. 
For the most part, the eggs are laid and the larvae undergo their development in 
excrement; but the choice of the female does not seem to be always restricted to 
matter of this sort, since she sometimes selects meal, bread, or fruit, for the 
purpose. These flies are liable to the attacks of a parasitic fungus ( Empusa 
muscce) which causes their death, and in autumn it is not uncommon to find their 
bodies killed by this means, with the abdomen much distended, and showing the 
soft membrane between the segments. The common blue-bottle or blow-fly 
(Calliphora erythrocephcda) is too well known to need description. One of the 
most noteworthy features connected with this fly is the extraordinary keenness of 
the sense—perhaps smell, which enables it to discover the whereabouts of carcases, 
however small, or of particles of meat. In these it hastens to lay its eggs ; and in a 
longer or shorter time, according to temperature, the eggs hatch, and the larvae, 
