USES OF INSECTS. 



105 



or animal matter ; for example, many caterpillars. A few species live in 

 society, such as bees, ants, wasps, &c. 



S31. By obtaining a general knowledge of the abodes of insects, it is 

 evident that the observer of the economy of insects will be able more satis- 

 factorily to combat many that are injurious to him ; as thus he can, with 

 little trouble, greatly diminish or entirely annihilate those which he has 

 ascertained to live in society, or in places of easy access. 



Subsect. 5. Uses «/ Insects. 



832. There are among insects no very inconsiderable number from which 

 man derives, in many respects, immediate and important uses. We need 

 here only to mention the bees and the silkworm. The dijBFerent sorts of gall- 

 nuts, ingredients so essential to dyeing and the manufacture of leather, are 

 the productions of several insects, namely, the gall-flies, which wound 

 with their ovipositor various parts of oaks, &c., in order to deposit their eggs 

 in the cavity, and which produce these useful excrescences. The most 

 durable and most beautiful red (cochineal) we owe to a small insect, the 

 Coccus cacti. Another, nearly allied to the above-named insect. Coccus 

 manmparus, is supposed to have saved the lives of the Israelites in their 

 journey out of Egypt, for they would have died of hunger if they had not 

 been provided with manna, — a sweet nutritive substance, which is regarded 

 as identical with the material which, in consequence of a wound caused by 

 this insect on the Tamarix gallica mannifera, trickles on the ground. 



883. The Cantharides, or Spanish blister-flies, are an essential article of 

 medicine. Many insects accomplish the fructification of different plants. 

 Whole nations in other quarters of the globe live on locusts. Many 

 mammalia, a number of birds, amphibious animals, and fishes, live entirely 

 on insects. 



384. A great number of these creatures even live upon other species of 

 insects, and destroy them : thus preventing the hurtful from preponderating, 

 and disturbing the balance in the economy of nature. To these belong 

 chiefly the /chneumonidse and spiders. 



385. Lastly, how many diseases are obviated, particularly in warm cli- 

 mates, by insects speedily consuming dead animal substances, and thereby 

 preventing the generation of noxious gases ! 



Subsect. 6. Means contrived by Nature to limit the Multiplication of Insects. 



836. Many appearances in nature, even such as at first cause anxiety and 

 care, on account of their injurious consequences, are found to be in many 

 respects highly beneficial and salutary, although we may not always under- 

 stand them. Thus, continued rain, which in many respects is extremely 

 hurtful, contributes greatly to diminish the number of noxious insects, and 

 for a series of years renders them entirely innocuous. This continued rain 

 may, for example, take place at the pairing time of certain insects, which 

 will greatly obstruct them ; or at the time when the insects are in the cater- 

 pillar or larva state, when thousands die in consequence of bad weather, 

 and our fields, orchards, and woods are cleared of a dangerous enemy for 

 many years. Thus in the spring of 1882, after incessant rain, Kollar saw 

 the caterpillars of the white-thorn butterfly (Papilio cratse'gi), which for 

 many years had not only stripped all the hedges, but also done considerable 



