VARIOUS DIPTERA 181 
beak-like prolongation of the head in Syrphidae, which is correlated with an enlarge- 
ment of the cavity for receiving the proboscis. 
‘Among purely suctorial flies, the species of Emps carry their thin, straight 
proboscis directed downwards, and prefer to use it in that position. They therefore 
chiefly resort to erect flowers, into which they can plunge this organ vertically down- 
wards. If the flower is tubular, and so much elongated as to make it necessary, they 
thrust the whole head down into the tube, an action which its small size renders 
possible, even when the tube is tolerably narrow. The chitinous piece formed by 
coalescence of the mandibles is broadened (e.g. in Empzs tesselata) into a sharp, 
lancet-shaped plate, which, guided by the elliptical end-flaps, is used for boring into 
juicy tissue, such as the inner wall of the spur in species of Orchis. Any consider- 
able increase in length in a downwardly-directed proboscis is clearly impossible 
without the development of a joint. 
‘In the Conopidae, when the proboscis, which is still carried downwards, is of 
considerable length, it is bent like a knee at its base or in the middle. In the latter 
case the distal part folds back into the proximal, like the blade of a pocket-knife, 
thus enabling the proboscis still to be carried in a downward position. 
‘The species of Bombylus, on the other hand, carry their proboscis (which here 
also is too long to be carried downwards without folding) directed straight forwards, 
and permanently ready for action. ‘They thus obviously save time, for, without 
settling, they are able to insert the proboscis into nectar-yielding flower-tubes as they 
hover in the air, flying rapidly from one blossom to another. In length of proboscis 
they rival Rhingia, for in Bombylus major this organ is tomm. long, and in B. 
discolor 11-12 mm. They also approximate to Rhingia in their powers of detect- 
ing deeply concealed nectar. The species of Bombylius, like those of Empis, are 
also able to bore into succulent tissues. For the labium and the labrum which it 
encloses are gutter-shaped, and together form a tube in which the bristle-like 
maxillae, with the broad, strong, and pointed mandibular piece, move backwards 
and forwards. The labrum itself is drawn out into a stiff and extremely fine point, 
All these piercing structures, held between the long, narrow end-flaps, can easily 
penetrate soft tissues. I have often seen species of Bombylius thrust their proboscis 
into nectarless flowers (e.g. B. canescens Jk. into Hypericum perforatum), and 
I imagine that here the boring-apparatus was being brought into action. 
‘While, so far as I know, the species of Bombylius and the Conopidae seek 
only the juices of flowers, very many other anthophilous flies are in the habit at 
times of sucking all kinds of other fluids and damp substances, these often being of 
uncleanly nature. Species of Lydstalis, for example, may often be seen feeding 
eagerly in gutters, and species of Scatophaga and Lucilia on dung. Sarcophaga 
licks putrid flesh with relish, and even Volucella bombylans, so common on flowers, 
I noticed (in May, 1860) feeding on a floating carcase, returning repeatedly to it 
when driven away.’ 
To this account by Hermann Miiller, E. Loew (‘Blumenbesuch,’ I, pp. 111 
et seq.) adds that the mode of life and the structure of the proboscis in the great 
family of the Muscidae are extremely varied. This investigator, who has studied with 
particular care the structure of the insect proboscis, states that, in addition to 
