485 



Natural Checks. Although economic entomologists have 

 already tested many valuable insecticides, and so compounded them 

 that they kill insects but leave plants uninjured, yet there is, in 

 keeping noxious insects in check, even more efficacious allies than 

 the spray pump and the insecticidal mixtures. 



All insects, injurious or beneficial, have many natural enemies 

 of their own to contend with. Some are of a higher order in the 

 scale of animal classification, such as lizards, frogs, and other 

 reptiles ; birds, moles, etc. Others, more numerous, belong to the 

 insect world itself. 



Amongst these, some which attack noxious insect pests from 

 the outside, and either devour them or suck their vital juices, are 

 called predaceous insects, e.g. ladybirds, spiders, soldier bug, black 

 ground beetle. 



Others, called parasitic insects, differ from the predaceous 

 ones, in so far as they live inside the bodies of their victims, and 

 ultimately kill them. Amongst these parasitic insects the more 

 numerous are ichneumon wasps, which entomologists classify 

 amongst the hynienopterous, or four- wing flies. Another class of 

 flies, with only two wings, and for that reason known as dipterous 

 insects, contribute largely to the ranks of insect parasites. 



But even these parasites are frequently subject to the attack of 

 still smaller parasites, which prove as fatal to them as they did to 

 their insect hosts. The first of these parasites are, for that reason, 

 known as primary parasites, to differentiate them from the second, 

 called secondary parasites. When introducing parasites into an 

 orchard or a garden, therefore, it is of the greatest importance that 

 we should have a clear idea whether we are introducing an ally 

 which will prove beneficial, or whether we will add to the list of 

 our pest enemies another insect which will prove mischievous. 

 Such a work is better left in the hands of experienced people, and 

 may prove a dangerous tool in those of the tyro gardener. 



Besides insect parasites, injurious insects are also attacked \yy 

 even more minuscule foes. These are germs of contagious diseases, 

 which, at times, stop an insect plague with remarkable suddenness. 



These germs are of two orders : some bacterial and inward, 

 e.g. green potato and tomato caterpillars ; others, superficial, cover 

 their victims with silklike threads, and belong; to the mould family, 

 e.g. the African locust fungus the housefly fungus. 



GARDEN AND ORCHARD CROPS THEIR PESTS AND 



REMEDIES. 



In a tabular form, I have grouped those insect and fungoid 

 pests which attack our orchard and garden crops. A few words 

 concerning the more prominent amongst these pests will follow. 



