part u.] THE INSECTS WHICH VISIT FLOWERS. 41 
when at rest. Such a state of things is found in Lthingia, where 
the proboscis (11 to 12 mm. long), exceeds in length the whole body 
(10 mm.), and is not surpassed by that of any indigenous fly.! 
In anthophilous insects, the power to detect hidden honey ad- 
vances parallel to the structural adaptations for securing it. When 
Sprengel described flies as stupid insects, incapable of finding 
out honey which lay concealed, that statement applied to the great 
majority of short-tongued forms, but not at all to forms with 
long proboscides, such as the Syrphide, Bombyliide, Conopide, and 
Empide. 
Rhingia takes a foremost place in intellectual acuteness, as 
in the length of its proboscis, and there is, I think, no flower 
which affords honey attainable by it, that it does not discover 
and make use of. For instance, the deeply-hidden nectaries 
of the Iris are more frequently visited by Rhingia rostrata 
Fia. 6.—Proboscis of Rhingia rostrata, L. 
1.—Side view of head with retracted proboscis. 
2.—Ditto, at the moment when the proboscis begins to unfold. 
8.—Ditto, with fully extended proboscis. 
4.—Head, with retracted proboscis seen from below, twice as much magnified as in the three 
first figures. 
Lettering as in Fig, 2. 
than even by humble-bees, though Sprengel (p. 74) considers 
that no insects save bees can find them, and adds that this 
goes without saying in the case of flies, which are so obviously 
too stupid. 
But even in the Syrphida, only a few species have acquired so 
highly specialised a proboscis as Hristalis: the great majority have 
a proboscis formed on a similar plan, shown in Fig. 7. The labium 
is much shorter, its extensible middle jomt is wanting, the 
terminal flaps are swollen and cushion-shaped, and there is a 
corresponding diminution in intellectual power. Of the families 
of Diptera besides Syrphide, the Muscide, Stratiomyide, Bombylude, 
Conopide, and Empide are of some importance in the fertilisation 
1 Bombylius discolor, Mik., alone equals it in the length ofits proboscis ; Bombylius 
major, L., approaches it (10 mm.) 
