80 E. P. Sfcebjbing — "Economic Entomology. [An; 



The well-known Phylloxera of the vine is an insect of this kind and 

 for years the root-feeding form was described as a different species. 

 Again there are other insects which at one stage of their life-history 

 are able to produce young in large numbers parthenogenetically, these 

 maturing very rapidly and doing the same in their turn, the process 

 continuing for several months on end from the spring to autumn. 

 At this latter season a sexual generation is produced which lays the 

 winter eggs, which in the succeeding spring gives rise to the partheno- 

 genetic females. It thus becomes obvious that the efficient study of 

 Economic Entomology requires a previous very considerable and intim- 

 ate acquaintance with the habits of the different groups of Insects and 

 also requires one to be prepared for the startling vagaries the effect of a 

 semi-tropical or tropical climate has upon them in their various life 

 cycles. It is this that makes it difficult, if it does not lead to absolute 

 confusion, to make use of observations and remedial measures which 

 have been worked out or found effectual in other countries. The theory 

 that what holds good for, say, Europe or America, will be equally 

 applicable in a country like India is a fallacy which cannot be too 

 widely exposed. To act on the assumption that because an Insect has 

 such and such a life-history in, we will say England or North Europe, 

 appears at such and [such times, etc., that therefore we know the life- 

 history of that same insect (for some pests are cosmopolitan in their 

 range) or of closely allied forms, in a country like India is not only to 

 involve the science in a dangerous and hopeless medly of inaccurate 

 postulations and assumptions, but also to risk wasting large sums of 

 money in endeavouring to combat pests who are not at the time in the 

 stage at which the remedial work has a chance of meeting with success, 

 and whose life-history in this country is quite different to what it is 

 supposed to be from European analogies. A well-known and experienced 

 Entomologist, Mr. Walter F. H. Blandford, who worked at Economic 

 Entomology for the India Office for several years and consequently obtain- 

 ed a wide knowledge of this phase of the subject, used to continually 

 reiterate his warnings as to the danger of taking anything for granted in 

 a country like India, and my own experience has proved over and over 

 again the justice of his contention. The Economic Entomologist in 

 India must go into the field or orchard, plantation or forest and study 

 the pest carefully on the ground though, the inns and outs of a series 

 of life cycles before he can safely prescribe remedies on a large scale. 

 Even in the outer Himalayas, where conditions are more similar to 

 Europe and North America, the investigator must proceed warily and 

 deduce nothing 'because it is so in Europe' without first carefully 

 verifying his opinions by observation. 



