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On July 16, I was called to a peanut field in Santa Rosa County. There I met with producer Steven Godwin, and CPS agronomist Greg Esco, to examine an unknown cluster of aphids found in the field they were scouting for lesser cornstalk borer. The scientific jury is still out on identification of the mystery insect, and its potential impact.

The photos show the aphids in the first field examined. Walking through the field we found areas with large populations, while other areas had very light population and in some areas few or no aphids present. The producer elected to apply an insecticide treatment to the first field, greatly reducing the population.

Many other peanut fields have been scouted but we have not located a field with such a high number of these unknown aphids present as in the first field. One thing Mike and I noticed while scouting was the fields with aphids present also had significantly higher population of fire ants working the fields.

In the last few days we have returned to the original fields scouted for aphids. Some of the fields had received insecticide treatments and some had not. It was difficult for us to find live aphids to get a count and live samples for the scientist to process.

We did find colonies of parasitized dead aphids, or mummies, in the non-treated fields. This bug will probably be “officially” identified as the cowpea aphid. It has a broad host range with a preference for legume crops. It is known to occur in at least 28 states.

The cowpea aphid is relatively small, 1.5 to 2.5 mm long. The adult may be winged or wingless and is usually velvety black with a distinct waxy cover, while nymphs are smoky gray. Examine your field for these aphids somewhat in the same manner as scouting for lesser cornstalk borers. We found them down in the canopy at, and just above, the soil surface.

More information is expected within the next few days. We will know if this is a potential new pest of concern of peanuts and if management techniques are required. Contact John Doyle Atkins, srcextag@ufl.edu or Mike Donahoe, MikeD@SantaRosa.fl.gov for updates.

John Doyle Atkins

Permanent link to this article: http://okaloosa.ifas.ufl.edu/newsletters/2012/08/07/aphids-and-peanuts/