FLIES. The majority of the flies (Diptera) re sort to flowers for the little food they require in the imago state. And here the mouth-parts are very different in structure from those of bit ing insects, the long proboscis being a modifica tion of a portion of the labium, representing the tongue or 'lingua' of other insects. The beauti ful yellow, wasp-like drone-thes (Syrphidte). so abundant about flowers and so important as fer tilizers, depend mainly or exclusively on a floral diet; and here, as Maher states, "are found the most perfect adaptations to a diet alternately of pollen and honey." The complicated proboscis ends in two broad flaps. These flaps are "admi rably adapted for seizing the pollen, for grinding it down, and for passing it backward, the ap posed surfaces of the two flaps being closely set with parallel ridges of chitin, by which the pollen grains are easily held fast and shored into the entrance of the groove. Diptera, like the house and allied flies (Museidte, also the Stratiomyi the). visit flowers to obtain both pollen and honey.
These flaps are wanting in other flies, as the mosquito, and in the Bombyliida), which have enormously long tongues, as well as in other families (Empidte and Conopida-). and these flies visit flowers, probing then) for the honey alone. Now, in these flies the head itself is not espe cially modified, but in Rhingia the head is devel oped into a long snout, the tongue being longer than the whole body. This fly (one of the Syr phid:e) is remarkably intelligent, probing the deeply hidden nectary of the iris and many other flowers. The species of Empis carry their long, thin, straight proboscis directed downward; hence they chiefly resort to erect flowers. into which they can plunge their proboscis vertically. In all these flies there is great variation in the Shape and degree of specialization of the mouth parts, these being in intimate relation with the habits of these highly specialized insects.