THE SEASONAL CYCLE OP INSECT ABUNDANCE IN PUERTO RICAN CANE FIELDS

Abstract

Five years observations in fields of young cane in Puerto Rico indicate a marked seasonal abundance during autumn and early winter, of all caterpillars except those of Diatraea saccharalis F., the species noted being Laphygma frugiperda S. & A., Mocis repanda P., Panoquina n. nero F., P. coscina Herrich-Schäffer, Perichares c. coridon F. and Marasmia trapezalis Guenée. The yellow aphid, Sipha flava Forbes, is most abundant during the winter and again in late spring, especially in eastern Puerto Rico. The eggs of Diaprepes abbreviatus L. are most abundant in June and September, and on the south coast were found only during these months. Thonalmus chevrolati Bourgeois, a red .and blue Lycid beetle accidentally established at Guanica by introduction from Santo Domingo, has spread north to Coloso and east to Ponce. The twice-stabbed lady-beetle, Chilocorus cacti L., introduced to prey upon the scales attacking bamboo, feeds on many other kinds of scales, and at times is found in cane fields. The injury produced by a new species of mite, Tetranychus sacchari McGregor, simulates mosaic disease.