SPATIAL PATTERN OF THE IMMATURE STAGES AND TENERAL ADULTS OFPHYLLOPHAGASPP. (COLEOPTERA: SCARABAEIDAE) IN A PERMANENT MEADOW

Abstract

AbstractRandom counts of the white grubs,Phyllophaga fuscaFroelich andP.anxiaLeConte, in a permanent meadow did not conform to the Poisson distribution, there being an excess of uninfested and highly infested sample units over the expected number. But when the negative binomial series was fitted to the observed distribution, the discrepancies were not significant when tested by chi-square. Using a commonk, the distribution of the various stages may be described by expansion of (q-p)−k, when values ofkare as follows: egg 0.15, first instar 0.41, second instar 1.30, third instar 2.00, pupa 1.62, teneral adult 1.30. Aggregation resulted from the clumping of eggs at oviposition, and randomness increased with dispersal of the larvae. For all stages, the variance was proportional to a fractional power of the mean. Three transformations are offered for stabilizing the variance of field counts.