TIPULID.E. NOTACANTHA. TANYSTOMA. 199 



C. destructor, is known in America under the name of the Hessian 

 Fly ; this attacks the lower part of the stem of the wheat. The 



FIG. 525. CKCIDOMYIA DESTRUCTOR, and C. TRITICI, with the Larvae 

 of the latter feeding in wheat flowers, magnified. 



proper Tipulce, or Harry Long-legs, are the largest species of 

 the family. Their Iarva3 generally live in the earth, in the rotten 

 parts of trees, &c., and many of them do great mischief by feed- 

 ing upon the roots of grass and corn. 



794. Section II. NOTACANTHA. The second Section of the 

 Diptera contains three families, STRATUOMID^E, BERID^E, and 

 CCENOMYID^E, which do not attract much attention, although 

 some of the species contained in them are very abundant. They 

 are mostly small but gaily-coloured insects ; and are most nume- 

 rous in moist situations, in which the larvae are generally pro- 

 duced. Some of the larvae, as that of Stratiomys Chamcsleon 

 (Fig. 522), are completely aquatic; and respire, like the larvae 

 of the Gnats, by extending their tails to the surface, the spiracle 

 or breathing-pore being in that situation. They mostly feed 

 upon vegetable, rather than upon animal, juices. 



795. Section III. TANYSTOMA. The insects composing the 

 third section have usually a more perfect mouth than those of the 

 other divisions ; and they are also remarkable for the structure 

 of the head of the larvas, which possess two claw-like appen- 

 dages, by which they attach themselves to the substances that 

 afford them support. Many of the perfect insects are eminently 

 carnivorous or insectivorous ; as are also some of the larvae. 

 There is a genuine metamorphosis in this group ; the larva-skin 

 being cast off at the entrance of the animals into the pupa-state. 

 In this state they much resemble the perfect insect; the limbs 

 being inclosed in distinct sheaths, and folded on the breast. 



