314 AUSTRALIAN AGRICULTURE. 



a very little of any oily substance will close these small 

 openings, and smother the insect as effectually as 

 clasping the wind-pipe will smother a man. But oil is 

 injurious to plants. Hence oily substances, dissolved 

 with alkalis to prevent the oil injuring the plants, 

 are used for checking and killing insects. Fumigation, 

 from sulphur and carbon compounds mostly, has long 

 been in use, and is still effective where plants can be 

 covered. 



Friendly Insects. Were it not for the natural enemies 

 which plant lice, scales, &c., have, like all animals, they 

 would soon become destructive beyond the powers of man 

 to keep them in check. The best known destroyers of plant 

 lice are ladybirds (Coccinella) and their grub-like larvae. 

 Well-known ladybirds are about the size and form of 

 split peas. The perfect insect is of dull orange colour, and 

 usually has nine small black dots on the wing shells. 

 These insects lay their tiny eggs near the plant lice, and as 

 soon as the grub hatches out it proceeds to devour its 

 natural food. They may be often seen upon potato plants, 

 upon melon vines, and on other plants. The grubs vary in 

 colour on different coloured plants. They do not look nice, 

 but it is safe to conclude that when they are about more 

 disagreeable visitors are disappearing. The young of 

 various flies are also destructive to plant lice, upon which 

 the mother flies deposit their eggs. The young maggots 

 devour great numbers of aphides. 



Knowledge of Fungus and Insect Life. That some 

 acquaintance with the methods of insect life, even the very 

 rudiments of entomology, are useful to the agriculturist is 

 evident. It is during the early stages of insect attacks, the 

 same as those of fungus attacks, that the most effective 

 efforts to check or destroy them are made. An hour spent 

 then may prevent heavy losses more certainly than weeks 

 of toil, expenditure, and lamentation after the pests have 

 got a start. The skill is in being able to identify and check 

 the enemy at the beginning, and is a sort of skill which 

 young folks acquire rapidly and eagerly. They are soon 

 able to identify the enemy and their works, and the 

 presence of friendly beetles, ichneumons, and others, which 



