|Alfalfa is the prime food source for the dairy industry.|
|Blue alfalfa aphids cover a stem of alfalfa.|
|Examples of blue alfalfa damage. (Oklahoma State photo)|
|Minute pirate bugs are a natural enemy of aphids.|
- Randomly choosefive stems from each of four areas per field, noting if the average plant height is less than 10 inches, 10 to 20 inches, or more than 20 inches.
- Bend each stem sample over a white pan and tap; dislodged aphids will fall in. The stem can also be shaken into a sweep net if a pan is not available.
- Take sweep net samples for lady beetle adults and larvae, fungal-killed aphids, parasitized aphid mummies, and the presence of other predators such as syrphidflies and lacewing larvae.
- Record results on a monitoring form. A pesticide application may be warranted if natural enemies fail to keep the aphid numbers in check.