Survival of Overwintering Southwestern Corn Borers in Corn Stalks in Louisiana

Drastic reduction in the overwintering population of Diartraea grandiosella Dyar in old corn stalks in north Louisiana was found to occur. Results of a 2-year study whereby old corn stalks were systematically examined revealed that drastic reduction of the overwintering population was caused by predation on the larvae by the yellow shafted flicker, Colaptes auratus, from early January to mid-March. Overwintering populations of 30–40 larvae per 100 stalks were reduced by the birds to a 2–4 larvae per 100 stalks by early spring. A slight amount of natural mortality, attributed to disease, occurred. Results of examinations of overwintering larvae under large bird-proof field cages showed that low temperatures normally experienced in the test area did not adversely affect overwintering larvae in old corn stalks.