Population Density of the Pecan Weevi1 Under ‘Stuart’ Pecan Trees12

Abstract

Two methods were used to estimate the population of adult Curculio caryae (Horn) emerging under ‘Stuart’ pecan trees. Weevils were trapped and collected by enclosing the area under the tree within the drip-line with a tent of cotton or nylon cloth. By this method the population per tree in 1969 was estimated at 3785 weevils. The second method used 100 screen wire traps arranged in 5 concentric circles 5.0 ft apart except for the innermost circle of 7.5 ft from the tree trunk. By this method tree populations were estimated at 1762 weevils in 1968 and 6130 in 1969. In addition to population-per-tree estimates, the trap method depicted the distribution of the population at 100 different points under the tree, thus reflecting the effects of positional factors. More adults emerged in the north and east quadrants than in the south and west, and emergence from the soil close to the trunk was above average.