After a brisk round of southerly winds and rains, some insects that are not year-round residents find their way to Oklahoma. Normally, potato leafhoppers are year-round residents of the Gulf coast states and gradually migrate northward with spring winds. Because of wind dispersal, potato leafhoppers are likely to be a pest of alfalfa from June to October. The potato leafhopper poses the greatest threat (if any) in the higher rainfall and humidity areas of the state. In western Oklahoma, high potato leafhopper populations are rare because hot, dry conditions normally prevail.  

The potato leafhopper adult is a light green, wedge-shaped insect about 1/8 inch long. The nymphs closely resemble adults; however, they are smaller, yellow, and wingless. Both adults and nymphs are very active; they can move sideways and backward as rapidly as forward when they are disturbed.  

Damage: Both adults and nymphs use their piercing-sucking mouth parts. to feed on alfalfa; however, the most serious damage is caused by the nymphs. Initial feeding damage is characterized by a wedge-shape yellow area formed on the leaf tip known as "hopper burn". (Sometimes confused with drought.)  

Heavy feeding causes the entire leaf to turn yellow and heavily infested fields take on a yellow color. Usually damage is greatest along field margins. Mowing ditches next to alfalfa meadows can increase chances of sustaining leafhopper damage because the leafhoppers move into the alfalfa.  

Due to their minute size, the best means of detecting leafhoppers before damage can be seen is a sweep net. Sample at least four areas across a field. In each area take at least 20 sweeps before counting the number of adults and nymphs. 
 

Treatment is justified at these combinations of alfalfa height and leafhopper numbers:  
 

  
Besides height and leafhopper density, one needs to consider yield potential and stand age before deciding to treat or not. Insecticides recommended for control include: Dimethoate, Methoxychlor, Parathion, Lorsban^® , and Furadan^® .