1903.] E. P. Stebbing — Economic Entomology. 77 



specialist, makes no pretence at working in a line foreign to him. The 

 difference may be said to be almost equally wide between the Economic 

 Entomologist and the Museum Entomologist. The latter especially in- 

 terests himself in the classifications of insects, gives names to new genera 

 and species ; considers, in the light of fresh discoveries, the re-arrange- 

 ment of the grouping of families or the formation of new ones, etc., and 

 keeps watch over the valuable type collections of the nation, all work 

 requiring careful training, deep reading, much microscopic labour, and an 

 enthusiasm for the subject. The Economic Entomolgist, on the other 

 hand, studies insects from a very different point of view. His aim is to 

 find out where the insect lives, what it feeds upon, the periods spent in 

 the various stages of its life-history, i.e., how long it spends in the egg- 

 stage, grub-stage, etc. Whether at one time of the year it lives upon 

 a certain kind of crop, changing its food plant later on or seeking neigh- 

 bouring patches of scrub jungle to lie up in when the fields of the plant it 

 is partial to are lying fallow. This knowledge enables him to draw out 

 his plans for attacking noxious pests. To him the fact that the insects 

 he has discovered and is studying are new to science is, though interest- 

 ing, quite of secondary importance. Their habits and life-histories and 

 the best means of combating them are his chief concern. To his com- 

 panion in the Museum he leaves the other portion of the work. 



With this brief digression we will now devote ourselves to a con- 

 sideration of how the Economic branch of the science, or the work in the 

 field, can best be studied, our object being the protection of vegetation 

 of use to man by discovering means to check undue increases of noxious 

 insect pests. 



With reference to the position of the Insecta in the Animal Kingdom. 

 Perl laps if I say here that insects lie roughly halfway up the 

 scale, i.e., halfway between the simplest animal, the one-celled Amceha 

 and that highly and complexly constituted being known as Man, having 

 as near relatives the crabs and lobsters, spiders and scorpions on the one 

 hand, and the centipides, and millipedes and, still higher up, the starfish on 

 the other, their position will be sufficiently defined for our present purpose. 

 In dealing with the subject it will be necessary to first consider briefly 

 the stages in the development of an insect. We all know what such an 

 animal is like and he who lays no claim to the slightest acquaintance eith- 

 er with their classification or varied modes of life is able in the general- 

 ity of cases to recognise an insect. The ordinary layman equally knows 

 that an insect passes through various stages of development. The gaudy 

 butterfly, gracefully floating on azure wings in the brilliant sunlight, 

 does not come into being as such and its transcendent beauty can no 

 more be perceived in its earlier stages than can the glorious loveliness 



