An ecological Study of the “Lucerne Flea” (Smynthurus viridis, Linn.)—II

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Abstract
Following the method of procedure already outlined, the life-history ofSmynthurus viridis, its bionomics insensu stricto, and the influence of environmental factors under controlled laboratory conditions, having been considered, the next step is an examination of the seasonal cycle of events as occurring in nature. Part II is, therefore, devoted largely to an analysis of the field data, coupled with an interpretation thereof as substantiated by critically planned and controlled laboratory experimentation; this reinforcement being rendered necessary on account of a multiplicity of factors acting simultaneously in nature. The chief difficulty in an investigation of this kind (as with all problems concerned with fluctuations in the numbers of organisms) lies in the fact that there are few methods for obtaining quickly and easily an accurate quantitative sample of the numbers and kind of organisms; and, secondly, there is the difficulty of finding (in a long-inhabited country like Britain) a “normal” environment,i.e., one in which purely natural agencies have been allowed free play over a sufficient interval of time to allow a state of equilibrium to have become established between the various members of the community to whichSmynthurusbelongs, in their relationship to the physical factors of the environment and to each other.