THE PRESENT POSITION OF ECONOMIC ENTOMOLOGY. A'il 



C. — Checks. 



I have placed in one section all those questions that turn on the 

 relations of one species to another, the problems of parasites, predators, 

 natural checks on excessive increase of a species. I believe I am correct 

 in saying that a complete study has never been made of the foes of any 

 one Indian insect ; we know little or nothing of the predaceous and 

 parasitic insects of this country. They are of profound importance in 

 regulating the increase of destructive insects ; they are bred from all 

 sorts of insects or are found feeding on them. A study of any group of 

 parasitic or predaceous insects would yield most interesting results. We 

 have much to learn before we can determine whether there is any way 

 of influencing them, of aiding them, or of controlling them in their useful 

 work. Some years ago the coffee planters of South India sent a man to 

 Australia to find beetles to eat the coffee scales ; they were not suc- 

 cessful and I think any one who had studied the question could have 

 given them better advice and spared their pockets. 



I include here all those problems that are concerned with the 

 " balance of life " and kindred phenomena. It is one of the ideals of 

 economic entomology to control the injurious insects by maintaining the 

 balanca of life, by preserving the balance between the parasite and its 

 host, the predator and its prey. It is because that balance is upset that 

 9ome species are able to increase so enormously and so rapidly. I 

 cannot enter into this question ; it demands a paper to itself. In time 

 we shall perhaps be able to work up to this ideal condition or to at least 

 understand something of it. The preliminary will be a study of these 

 predatory and parasitic insects, of insectivorous birds, lizards, bats, etc. 

 At present there is an almost clear field in this section. 



D. — Morphology, etc. 

 We may group together Morphology, Physiology, Embryology and 

 allied subjects in one section, as of little direct importance. We cannot 

 say of no importance ; a study of the digestive processes of caterpillars, 

 locusts and other plant-eating insects would possibly yield valuable results. 

 We use arsenic in various forms as a stomach poison, because we know, 

 it does poison insects ; I suppose it was first tried on account of its effects 

 on the higher animals. There is reason to believe that other compounds, 

 innocuous to ourselves, would prove poisonous to plant-eating insects if 

 we understood the physiology of digestion and could act on that know- 



