214 THE INSECT WORLD. 
and sometimes August, the caterpillar of which lives on the leaves 
of willows, poplars, and fruit-trees;-and the Poplar Hawk-moth 
(Smerinthus populi, Fig. 199), whose caterpillar (Fig. 200) lives 
on the poplar, the aspen, and sometimes on the willow and birch. 
The division of Bombycina contains the largest of moths ; and at 
the same time species of a middle and small size. These moths 
take no nourishment, and live only for a short time, long enough 
to propagate their species. They rarely fly during the day, 
only showing themselves in the evening. The group is dispersed 
over nearly all parts of the world, and may be recognised - by 
the antennz generally being cut like the teeth of a comb in the 
males, by their thick, strong bodies, and in the majority of cases 
by their large head, by their wings more or less large, and by 
their heavy flight. 
In the Bombycina are found the genera Sericaria, Attacus, 
Bombyx, Orgyia, Liparis, &e. 
It is to the genus Bombyx that the silkworm belongs, that 
celebrated insect called by Linnzus Bombyx mori, a name which 
reminds us at the same time of its most ancient denomination, and 
of the mulberry tree, on which these caterpillars feed. 
M. Guérin-Méneville has called the silkworm “the dog of 
insects,” for it has been domesticated from the most ancient times, 
and has become deprived of great part of its strength in the 
process. The moth of the silkworm can no longer keep its 
position in the air, or on the leaves of the mulberry when 
they are agitated by the wind. It can no longer protect itself, 
under the leaves, from the burning heat of the sun and from 
its enemies. The female, always motionless, seems to be ignorant 
of the fact that she has wings. The male no longer flies; he flutters 
round his companion, without quitting the ground. It ought, how- 
ever, to be possessed in the wild state of a sufficiently powerful 
flight. M. Ch. Martins found that after three generations reared in 
the open air, the males recovered their lost power. 
Before speaking of the different phases of the life of the silk- 
worm and the rearing of this precious insect, we will say some- 
thing about the origin and progress of the silk trade, one of the 
most important branches of commerce in the South of Europe and 
in the East. - 

