Colonization and Establishment of the Red Pine Scale, Matsucoccus resinosae (Homoptera; Margarodidae) in a Connecticut Plantation

Abstract

The horizontal and vertical distributions of the red pine scale, Matsucoccus resinosae B&G (Homoptera: Margarodidae) were studied in a 1.6 ha pure plantation of Pinus resinosa Ait. in Connecticut. Both cast skins of intermediate-stage larvae from the previous generation and settled 1st-stage larvae had a highly contagious distribution. More than 56% of the total number of larvae occurred in only 8 of the 40 plots. Only 23 of 80 trees supported a previous generation of the scale. Dispersal reduced the degree of contagion by 50% after a single generation. The densities of settled larvae and of cast skins were not correlated with the distance of trees from a previously-infested stand but their distributions strikingly resembled the pattern of a shelter profile, characteristic of wind-dispersed insects leeward of windbreaks. A significantly greater number of settled larvae and of cast skins occurred in the lower canopy. The least number of both occurred in the upper canopy. The densities of settled larvae and of cast skins differed significantly among the 10 trees. Branch exposure did not significantly influence scale density. The occurrence of settled larvae was significantly correlated with the density of the previous generation of scale on individual branches and on trees. Examination of cast skins on dead branches can be a valuable aid in determining population levels of M. resinosae on red pine.