INSECTS DIAGRAM 6 100 



on each side. These are called stigmata and are the openings 

 for fine vessels filled with air, which communicate with the 

 exterior by the stigmata. These vessels are called tracheae. 

 They have a fine silvery colour, and nothing is easier than to see 

 them by opening the abdomen of a cockchafer under water, with 

 a little care. All these channels, which look like threads of 

 silver, and which ramify in the middle of the organs of the 

 insect's body become visible immediately. It breathes by 

 means of these trachese. 



Insects lay eggs, which are often 

 very numerous. They take care to 

 deposit them in places where the 

 larva) which will emerge from 

 them will find the means of 

 living. If the larva is aquatic, the 

 insect though aerial, deposits its 

 eggs in the water. 



Insects, chiefly in consequence of 

 the great appetite of their larvee, 

 Eggs of bug on a leaf are injurious animals ; they are the 

 scourge of agriculture, and man suffers much more from them 

 than from tigers, lions, or venomous serpents. There are 

 certainly some insects which eat others, and are consequently 

 useful auxiliaries to man ; but there are not very many. And 

 it is on account of the devastation of insects that all the 

 insectivorous mammals and birds ought to be considered as the 

 greatest friends of agriculturists. Some insects however must 

 be mentioned, which, like the bee, the silkworm, and the 

 cochineal, are directly useful to man, but these are exceptions. 



Insects are divided into several orders, which are characterised 

 either by the structure of the mouth, or by the number and 

 texture of their wings. We shall mention each of them, and 

 state their distinguishing characters. 



