The seasonal occurrence of fall army worm (FAW) larvae, [Spodoptera frugiperda (J. E. Smith)], was monitored weekly in corn [Zea mays L.], sorghum [Sorghum bicolor (L.)], signalgrass [Brachiaria decumbens Staph.], and bermudagrass [Cynodon dactylon (L.)] in southeastern Louisiana during 1980–84. The earliest and latest dates of detection of FAW during the study were, respectively, April 19 and August 4 for corn, June 9 and August 18 for sorghum, June 2 and September 21 for signalgrass, and June 8 and October 6 for bermudagrass. FAW generations overlapped in 1980, but in the other years generations were distinguishable and often coincided on the various host plants. The results indicated that there could be at least six generations in one year. In each year there was one major, and usually one or more minor, population peaks on each host plant. The range of dates for the greatest population peak density was June 24 - July 18 in corn, June 17 - July 7 in sorghum, June 30 - August 23 in signalgrass, and July 7 - August 18 in bermudagrass. The highest observed population density was ca. 3 × 105 larvae/ha in corn and 3 × 106 larvae/ha in bermudagrass.
Author notes
1 Approved for publication by the Director of the Louisiana Agricultural Experiment Station as manuscript number 88-17-2004.