Yesterday, my lab crew went to the ISU Northeast Research Farm near Nashua, Iowa to assess plant stands and take initial aphid counts in my efficacy evaluation trial. My technician found five wingless soybean aphids in a V1 plant. This was certainly interesting, as it could mean uniform colony development starting before bloom. They looked at hundreds of plants, but only found one that was infested. Likely a winged female dropped off a few nymphs on that plant and kept moving. I would not expect to see soybean aphid this time of year, although ISU Extension and Outreach Field Agronomist Brian Lang always seems to find some during the first week of June. Interestingly, Bruce Potter (IPM Specialist for the University of Minnesota), has been finding soybean aphid pretty easily in emerged fields in southwest Minnesota.
We will keep our eyes open for additional aphid finds. To help your search in seedling soybean, look for lady beetles because the bright coloration is a good cue. They seem to find aphids at any infestation level. Sometimes ants will tend soybean aphid colonies, so you may see ants on small plants, too.