172 INVERTEBRATE ANIMALS. 
and Moths, the former being active by day (durnal), and the 
latter mostly towards twilight (crepuscular), or at night (xoc- 
turnal). In all the Lepidoptera the mouth of the adult insect 
is purely suctorial, and is provided 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 colours. The larve 
of the Lepidoptera (fig. 87) are generally known as caterpillars. 
They are worm-like, provided with masticatory organs fitted for 
Fig. 88.—Goat-moth (Cossus liguiferda) and caterpillar. 
dividing solid 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 Lepzdoptera are characterised by 
being active during the day-time, by keeping their wings mostly 
