30 THE entomologist's kecokd. 



such, for example, as the neuration of the wings in lepidoptera, valuable as 

 it is as a means of classification, necessarily only covers a small part 

 of a complicated question. We want to know not only the structure 

 of that framework and of the bodily organs, external and internal, but 

 all that was distinctive in the life of a species, before we can assign to 

 it its proper place in nature. We ought to know, for example, about 

 the egg and its contained embryo, how it is fertilised, where it is 

 deposited, the cause of the fantastic shape it in some species assumes, 

 whether it is laid singly or in clusters, Avhether naked or provided with 

 a downy covering, and Avhat purpose this serves. We want to know 

 of the larvae and of the changes, sometimes of startling magnitude, 

 that they undergo in their ecdyses, the special food-plants to which 

 they are attached, generally, or at different periods of their lives, their 

 habits as regards exposure or concealment, their selection of places for 

 pupation, the nature of the covering they provide for the pupa, and 

 the mode of extrication from it. We want to know all that throws 

 light on the limitations and the perplexing uncertainties of double- 

 broodedness, the varying extent to which different \nnppe respond by 

 rapidity of development to a heightened temperature, while some 

 obstinately resist it. We want to learn the habits of the imago, its 

 mode and time of flight, the nature of its enemies, and the extent of 

 their ravages ; what is the stimulus which, after a pupa has rested 

 through the summer and autumn, causes it to emerge on some day 

 in the middle of winter and leaves other pupae to remain for years in 

 that stage, how so many winter moths come to have apterous or 

 serai-apterous females, while all their males have ample wings, what 

 special protection they enjoy by concealment or mimicry or by 

 flaunted nauseousness. The remarkable results obtained by some 

 careful and accurate observers in recent times show how much there 

 is in these and similar investigations to reward careful observation, 

 which to be entirely useful should be very precise and detailed. 



Few subjects connected with entomology occasion more discussion 

 or are of greater economic importance than the relative abundance or 

 scarcity of some species of insects and their variable time of appear- 

 ance. A vast number of interesting records on these points are 

 scattered through the entomological magazines for many years ; these 

 would be much increased in value if a statement of the circumstances 

 which may have influenced the numbers or time of appearance of the 

 insects accompanied the records, for example, the temperature pre- 

 vailing some time before, the character of the preceding period, Avhich 

 in our variable climate must often be such as to throw the seasons 

 out of gear and cause a species to be born at an untimely period. Even 

 in the work of some leading observers there is often a remarkable 

 omission to state temperature, when the whole importance of the 

 observation depends on it. For example, we are told precisely what 

 the duration of the egg or pupal period was, information which is 

 usually of small value unless we know the prevailing temperature ; for 

 experiment has shown that a diminution of 6 degrees F., i.e., from 

 62" to 56^^, may lengthen the duration of the pupal period in some 

 Vansseids from 20-22 days to 40 days. 



To conclude, I revert to the unassailable position that it is the life 

 of an insect in all its stages which makes it of supreme interest. The 

 animal, endowed with " the little living will that made it stir on the 



