INSECTS 5 OAS 
but one carries a horn ; on the under surface are sixteen 
legs—three pairs of jointed legs in front, as in the larve of 
all insects—and five pairs of unjointed fleshy legs behind. 
The three pairs in front end in sharp points, whilst the first 
four pairs on the abdominal segments are armed at their 
base with a circle of hooks; these enable the animal to 
hold on to the surface of the objects over which it is 
climbing. 
Fig. 86.—Silkworm. 
When full grown the larva sends out from two holes 
below the mouth a fine yellow sticky substance, which 
hardens on being exposed to the air into a silky thread 
or fibre. In this silky material the larva wraps itself up 
completely, and prepares for its change into a pupa or 
chrysalis. The mass of silk-fibre, with the chrysalis 
enclosed, is called a cocoon. 
The pupa stage lasts from ten to fifteen days, during 
which time the larva changes into a moth. The moth then 
cuts its way out of the cocoon, and after living long enough 
to lay the eggs which are to develop into another genera- 
tion of silk-worms, it dies. 
Uses. The uses of the insect are obvious. From it is 
obtained the silk of commerce. The fibre is soft, pliable, 
lustrous, and immensely strong. It is woven into silk 
thread and silken fabrics, and forms a valuable export in 
many countries, notably in China, Japan, India, Turkey, 
Italy, and France. On the average it takes from 11 lbs. to 
12 Ibs. of cocoon to yield 1 lb. of reeled silk, and to obtain 
