Volume 62 Number 9 Date 06/22/2017
ROSE CHAFER - This insect is common this season, and light damage is noticeable in soybean fields on sandy soils in the southern two-thirds of the state. Defoliation levels have not exceeded the 30% threshold for pre-bloom soybeans in any field checked by DATCP as of June 20.
SOYBEAN APHID - Early colonies have been found in soybean fields from St. Croix County east to Outagamie County in the last three weeks. Densities are generally below two aphids per plant (200 aphids per 100 plants), with fewer than 20% of plants infested in most fields. The highest total count observed to date is seven aphids per plant, 19 per infested plant, on 35% of plants in Trempealeau County. Routine sampling for aphids should begin by early July.
SAND CHAFER - Low to moderate populations were encountered in soybeans and corn near Richland Center on June 21. The adult beetles, notable for their similarity to Japanese beetles and an attraction to light-colored clothing, are not known to cause economic damage to crops, though injury by the immature grubs to potato tubers has been reported. Only minor leaf feeding was observed in the soybean fields with significant numbers of chafers.
-- Krista Hamilton, DATCP Entomologist