Fleahoppers and Lygus

Cotton Fleahopper Adult
Kate Harrell

Howdy,

  This week I have seen low thrips numbers and low fleahopper numbers in the fields in the Wharton, Jackson and Matagorda county area. The threshold for thrips is an average of 1 thrips per true leaf until the 5th leaf stage. While leaf cupping and curling can be signs of thrips damage, most of the curling I've seen this year was due to wind damage, not thrips.

  I saw cotton fleahoppers in lower numbers than last week in squaring cotton fields this week. The highest population I saw was in a field near Palacios again, with 13% of plants with fleahoppers, and more than half of those were early instar nymphs. This field was treated last week before the rain, and had 45% fleahoppers present before treatment. In another field a little off 35 near the Jackson/ Matagorda county line I found 3% with mostly adults present. Two other locations I visited with squaring cotton in Wharton county near the crescent area had 1% and 2% fleahoppers present. This insect feeds on plant materials, and will feed on cotton squares. Keep a sharp eye out for this insect, the adults are very flighty and are often easily scattered when walking fields. I try not to let my shadow hit a plant before I get close enough to look at it so I can see the adults before they fly. Above I have two photos of the adult insect and one of a nymph. The nymphs of these insects are also quite small, about the size of an aphid. They are also a pale green color, but lack wings. They lack cornicles (tailpipes) that an aphid would have, and tend to be more mobile than an aphid. Fleahopper nymphs also lack the bands on the antennae a few other species of plant bugs have, and have a similar body shape to the adult bug.

Cotton Fleahopper Nymph
Kate Harrell

Cotton Fleahopper Adult
Kate Harrell

  Fleahopper feeding will cause squares to drop. Plants can recover for and compensate for some square loss, but the threshold for fleahoppers is 15-25 per 100 plants. I check for fleahoppers by inspecting the plant terminals once they start squaring. I look at 25 plants per stop in the field, usually checking 100 plants total in an 80-100 acre field, more if the field is larger.

  The chart above with action thresholds if from the cotton insect guide, and the one below containing insecticide suggestions is from cottonbugs.tamu.edu.

Lygus Bug Adult
Kate Harrell

  This week in a field near El Toro I spotted two Lygus bugs on cotton. I have seen these insects on the weeds in field margins and in ditches in all three counties as well. This insect can feed on cotton squares, blooms, and small bolls. This can cause square loss, damaged anthers in blooms, and boll loss. The threshold for this insect is in the chart below. I am not currently concerned about damage from these insects since they are mostly in weedy margins. Once we start getting our weeds more under control, they could definitely pose a threat. The action thresholds for this insect are included in the chart below.

  I am currently looking for sugarcane aphids in sorghum fields as well. I've found them with little difficulty in johnson grass, but have not located them in field in any of my counties yet. If you have some, please let me know and I can confirm their presence in the county for our sugarcane aphid mapping project.

  Mosquito control is on many people's minds with the recent rains. Check out this publication on backyard mosquito control and this website on insect information and control options.

  If you're not sure what kind of insect you have, feel free to drop it by the Wharton county office.

  Have a good weekend, everyone!

Sincerely,

Kate

Looking for more information? Check out the Cotton Insect Guide

Need help with weed control? Check out the Weed Management Guide