Cotton Fleahopper, Pseudatomoscelis seriatus.
Adult cotton fleahopper.
If small squares (immature flower buds) turn brown and drop to the ground, the problem could be physiological or the damage may be caused by fleahoppers. If more than 10 to 20 percent of the small squares are lost in pre-bloom cotton, examine the plants for fleahoppers. A fleahopper is a 1/8 inch long, yellowish-green insect. It has an elongated, oval-shaped body that is slightly flattened over the top, which is typical for most true bugs. Adult fleahoppers have a few dark spots near the rear of the upper surface of the back. Nymphs may be white to light green, small and appear to be all legs and antennae. Alternate hosts are croton and silverleaf nightshade, so damaging infestations are more likely where these weeds are abundant.
Fleahoppers are not uncommon in Kansas cotton fields, but populations often remain below threshold levels. Begin scouting for fleahoppers when cotton reaches the six-leaf stage. Scouting may be difficult because adults may jump from plants if they see a shadow. During the first three weeks of squaring, the economic threshold is approximately 25 to 40 fleahoppers per 100 terminals with 10 to 15% blasted squares. Other sampling techniques involve the use of a drop cloth or sweep net. When sampling with a drop cloth, the drop cloth is placed between the rows and the plants are shaken vigorously over the cloth. Treatment should be considered when counts range between one bug per 1 foot of row to one bug per 3 feet of row. With a sweep net, the threshold ranges between 1 and 1½ bugs per 10 sweeps.
These insects attack squares in very early stages, so if square retention is 75 percent or greater there is probably not a significant fleahopper population. Because of the short growing season in Kansas, treating fleahoppers in August after bloom begins is rarely economical. In most cases, late-developing squares contribute little to increased yields and there is a chance any treatment will kill beneficial insects, possibly resulting in other pests such as bolllworms escaping control. Any secondary pest resurgence would offset the advantages of protecting later squares from fleahopper damage.
Many potential pests are under biological control in cotton, so whenever significant numbers of fleahoppers are found, select insecticides that have the least impact on beneficial arthropods, especially those which require consumption by the insect. Use lower rates and do not try for 100 percent fleahopper control.
Please refer to the most recent Cotton Insect Management Guide for material rates and control options.
Page last updated 10/31/2013 by J.P. Michaud.