290 INSECTS. 



said to be imperfect. The eyes of insects are either 

 compound, composed of numerous lenses, amounting in 

 certain butterflies to thirty thousand, or simple, called 

 stemmata, the latter alone being found in the larvae, 

 although in some of the beetles the larvae have eyes in 

 the head and tail both. They are often long in matur- 

 ing ; one species of locust, as is well known, remains 

 seventeen years before coming to perfection, and many 

 other families continue several years as larvae. Some of 

 the larvae live in the earth, some in wood, and others 

 under water ; some hide themselves in a cocoon ere their 

 metamorphose is effected, others build houses of stones 

 or sticks, others have no protection ; but all are wonder- 

 ful. One swims upon the water, another walks upon its 

 surface, a third crawls along at the bottom, although the 

 majority live upon dry land. In defence they use a 

 sting, simulate death, eject a poisonous liquid, or emit 

 an offensive smell. The eggs mature in the running or 

 stagnant water, in the ground, in the limbs of trees, in 

 the foliage and stems, or in the fruit. Grasshoppers in 

 the East, grubs among savages, snails among French- 

 men, ants among Brazilians, locusts among prophets, 

 and, if all reports are true, certain minute parasites 

 among Italians, have furnished pleasing and nutritious 

 food. 



But of all the marvels of insect life, that which is least 

 consonant with nature and least credible to human 

 understanding, is the fact that they appear spontaneously. 

 Why should a few drops of rain in a dusty road produce 

 animalculae never seen before ? "Why should a little per- 

 manent dirt originate two distinct parasites, according as 



