The Development of Pineus strobi (Hartig) (Adelginae, Phylloxeridae) on White Pine and Black Spruce

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Abstract
Pineus strobi (Htg.) feeds on eastern white pine, where the sedentary apterous form reproduces itself repeatedly without the sexual form. The insects overwinter as immature females mostly in the third instar. Some eggs laid in spring produce winged forms, but most eggs produce apterous forms. Winged forms migrate to black spruce where they settle on the needles, lay eggs, and then die. The eggs hatch, but the immatures soon perish. On pine the crawler stage is the only one, except the adult alate form, that is capable of dispersing. In 1960 the bulk of the population passed through five generations. Although P. strobi can survive in shady areas, it is not found on bark exposed to sunlight for long periods because air temperatures of 30 °C. or above are unfavorable to it. The mouthparts are inserted intracellularly and extend at least into the outer tissues of the live phloem. During the summer, populations of P. strobi were extremely small due to predation. The three commonest insect predators were: Chilocorus bivulnerus Muls., Microweisea marginata LeC. and Leucopis simplex Loew. Other associated organisms had little effect.

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