Timing of Treatments for Control of the Irregular Pine Scale

Abstract

Sprays of carbaryl or malathion at a rate of 1.0 lb active toxicant per 100 gallons of water afforded excellent control of Toumeyella pinicola Ferris (Homoptera: Coccidae) on Monterey pine in northern California when applications were made between mid-June and mid-July. Earlier or later applications were less effective. The peak of emergence of crawlers on twigs with a south or west exposure occurred as much as 1 month earlier than on twigs with a north or east exposure. The effectiveness of mid-June to mid-July applications was correlated with peak emergence on a whole-tree basis. There was evidence that either malathion or carbaryl was capable of killing scales which were recently established. A parasite, Coccophagus lycimnia (Walker) (Hymenoptcra: Aphelinidae), destroyed a low percentage of the female scales.