Uses of Insects. 



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 different 

 sorts of gall-nuts, ingredients so essential to dyeing and the manu- 

 facture 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 manniparus, is sup- 

 posed 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 pro- 

 vided 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. 



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

 medicine. Many insects accomplish the fructification of different 

 plants. (See the interesting and instructive work on the fertilization 

 of orchids by Mr. Darwin.) Whole nations in other quarters of the 

 globe live on locusts. Many mammalia, a number of birds, amphi- 

 bious animals, and fishes, live entirely on insects. 



A great number of these creatures even live upon other species 

 of insects, and destroy them : thus preventing the hurtful from pre- 

 ponderating, and disturbing the balance in the economy of nature. 

 To these belong chiefly the Ichneumonidse and spiders. 



Lastly, how many diseases are obviated, particularly in warm 

 climates, by insects speedily consuming dead animal substances, and 

 thereby preventing the generation of noxious gases ! 



Means contrived by Nature to Limit the Multiplication of Insects. 



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 understand 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. Thus in the spring of 1832, after incessant rain, 

 Kollar saw the caterpillars of the white-thorn butterfly (Papilio 

 crataegi), which for many years had not only stripped all the hedges, 

 but also done considerable injury to the fruit-trees, dying by 

 thousands, as if of a dropsy. The caterpillars swelled, became weak, 

 and died. If they did attain the pupa state, they suffered from the 

 ^anie evil, and the perfect insect was very rarely developed, on which 

 account the gardens in the following years were uninjured. 



