Non-Arsenical Stomach Poisons for Grasshopper Control

Abstract

Grasshoppers, as a rule, are not a serious pest of citrus trees over three or four years old. During the fall of 1931, they did severe damage in some orange groves in the central part of the State. Due to recent legislation prohibiting the use of arsenicals in citrus groves, except under special permission, it was necessary to make some tests of non-arsenical stomach poisons to control these pests. The grasshopper doing the most damage was the Bird Grasshopper, Schistocerca americana. It is one of our largest grasshoppers, long and slender, a powerful flier, and very active, especially on sunny days. It is evidently a sun-loving insect, as the trees were most severely damaged on the sunny side. The grasshoppers used for the following experiments were collected from one of the infested groves. Wire screen cages, 12x14x18, were used in the dusting, spraying, and a few of the bait tests. The majority of bait tests were made in cages of the above size but having no bottoms. In each test, potted citrus plants were put into the cage, or the bottomless cages were placed over young citrus trees in the nursery. In almost every case the tests were started the day after the grasshoppers were collected. Kalo, a material made up of 96 percent sodium silicofluoride, gave very good results when used in a bran mash. Kalo used at the rate of 3 pounds to 50 pounds of bran, 1 gallon of syrup and approximately 10 grapefruit, gave a 100 percent kill in two