225 
Many species of larvee can jump or spring for a distance 
of several inches. This they accomplish by folding the body 
until the posterior and anterior extremities meet, and by the 
aid of stout spines on the anal segment, or some means not yet 
precisely described, are clasped together; then the sudden 
relaxation of the hold causes the whole body to be thrown 
upwards and outwards. The species of the genus Diplosis are 
according to Loew the possessors of this habit. Its use to the 
larva is manifestly to aid it on leaving the gall, as many do, and 
seeking suitable quarters for pupation. 
The mouth parts are exceedingly minute and most difficult 
to separate out. No piece of microscopic anatomy requires 
greater care and patience. 
Ratzburg thinks they consist of a horny (chitinous) ring, 
through which protrudes a lip (labium) used as a sucker. In 
the Wheat Midge they are more than this, and a rudimentary 
mandibular process is certainly present. A pair of two-jointed 
appendages forms part of the anterior portion of the head 
segment; but whether these are palpi, as Ratzburg and Dufour 
thought, or rudimentary antennz (Osten-Sacken), seems yet to 
be doubtful. 
The most striking feature of the larva of a Cecidomyid, is 
a hard chitinous organ on the ventral face of the body in the 
middle line, projecting from the third segment. It has received 
a variety of names, and many conflicting views have been taken 
as to its function and homology. Nicholas Wagner in his cele- 
brated paper on a viviparous larva which belonged to this family, 
“Beitrag zur Lehre der Fortpflanzung der Insecten Larven,” 
(Zeits. £. Wissensch. Zool. Vol. XIII, p. 514), describes it as a 
borer, with head, (spitze), shaft, basal portion and muscles of 
attachment, and gives an admirable figure of it. He considers 
its function to be that of a boring apparatus. ‘‘Um sich in 
harten Holze den Weg zu erdffnen ist die Larve mit einem 
besonderen Apparate bewafinet. Es ist dies ein spitziger 
horniger auf dem dritten Segmente befestiger Auswuchs.” 
Hanin (op. cit. XV. 375) thinks this borer of Wagner is used asa 
means of facilitating progression by aiding the act of springing. 
