OKDERS OF INSECTS. 



159 



The Diptera constitute one of the largest orders of insects ; 

 the House-flies and Flesh-flies (Musca), the Gnats ( Culex), the 

 Crane-flies {Tipula), the Forest-flies {Sippobosca), and the 

 Gad-flies {Tabanidm), constituting good examples. 



Oedee IX. Lepidopteea (Gr. lepis, scale ; pteron, wing). 

 — This well-known and most beautiful of all the orders of in- 

 sects comprises the Butterflies and Moths, the former being 

 active by day (diurnal), and the latter mostly toward twilight 

 {crepuscidar), or at night {nocturnal). In all the JLepidoptera 

 the mouth of the adult insect is purely suctorial, and is pro- 

 vided with a spiral trunk fitted for imbibing the juices of 

 flowers. The wings are four in number, and are covered more 

 or less completely with modified hairs or scales, which are 

 pretty objects under the microscope, and from which the wings 

 derive their beautiful colors. The larvae of the JLepidoptera 

 (Fig. 71) are generally known as caterpillars. They are worm- 

 like, provided with masticatorj' organs fitted for dividing solid 



Fig, 71.— Large white Cabbage-butterfly (Pontia brassiem). a Larva or caterpillar; 6 

 Pupa or chryBalis; c Imago or perfect insect. 



substances, possessing false legs in addition to the three pairs 

 proper to the adult, and having attached to the under lip a 

 tubular organ or spinneret, by which silken threads can be 

 manufactured. 



The butterflies or diurnal Zepidoptera are characterized by 

 being active during the daytime, by keeping their wings most- 



