. Cooperative economic insect report. Beneficial insects; Insect pests. - 1030 - SALT-MARSH CATERPILLAR (Estigmene acrea) - WISCONSIN Larvae common on corn silks in many fields of corn examined. (Wis. Ins. Sur.). SOUTHERN CORNSTALK BORER (Diatraea crambidoides) - NORTH CAROLINA - Infesting most stalks in small field of late-planted corn in Camden County; 2-4 larvae present in each stalk. Infestation 70 percent in adjoining field of mature corn. Some Infestation noted in most fields checked in county. (Tuten, Mount). CORN ROOTWORMS (Diabrotica spp.) - SOUTH DAKOTA - D. virgifera (western corn r
. Cooperative economic insect report. Beneficial insects; Insect pests. - 1030 - SALT-MARSH CATERPILLAR (Estigmene acrea) - WISCONSIN Larvae common on corn silks in many fields of corn examined. (Wis. Ins. Sur.). SOUTHERN CORNSTALK BORER (Diatraea crambidoides) - NORTH CAROLINA - Infesting most stalks in small field of late-planted corn in Camden County; 2-4 larvae present in each stalk. Infestation 70 percent in adjoining field of mature corn. Some Infestation noted in most fields checked in county. (Tuten, Mount). CORN ROOTWORMS (Diabrotica spp.) - SOUTH DAKOTA - D. virgifera (western corn root- worm) adults ranged 3-4 per stalk in field of corn in Lincoln and Turner Counties Diabrotica spp. adults averaged 8 per plant further north in Moody County where silks not entirely brown. Mixed population in area approximately 60 percent D. longicornis (northern corn rootworm) and 40 per cent D. virgifera. Mating prevalent in all fields checked. Some fields of corn observed in eastern counties showing signs of drought. (Jones). MINNESOTA - Survey completed in southern portion of State. (See CEIR 15(35):993-994 for preliminary results ) Consider- able reduction in number of D. virgifera indicated, especially in southwestern counties. The accompanying map represents precentages of D. longicornis and D. virgifera found during survey. Also see map CEIR 15(201:4761: (Minn. Ins. Rpt. ) .. Upper figure = northern corn rootworm western corn rootworm NORTHERN CORN ROOTWORM (Diabrotica longicornis) - WISCONSIN - Ranged 0-27 (average 12) per 10 corn plants in Grant County, 0-12 (average 4) per 10 plants in Crawford County and 0-60 (average 19) per 10 plants in Vernon County. Popu- lations generally high in eastern Rock and western Walworth Counties; average 4 per plant; this average in fields with yellow silks. Much leaf feeding on corn beginning to tassel present in area. Resistant strains of D. longicornis definitely demonstrated in several fields in Rock County treated for several
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