This May, a herd of Azalea Sawflies defoliated, but did not kill, Erika’s azaleas. I base my identification by their food choice. Actually two species of Azalea Sawflies exist. Although they are in different genera, they are so similar in the larval stage that they defy identification. The larvae develop into stingless wasps.
Azalea Sawflies feed until only the leaf’s mid-vein remains. Fortunately only one generation of sawflies appears per year. Aside from squashing them between your thumb and forefinger, by the time the larvae are as large as the one in my photo, there is not much you can do. Younger larvae do most of the damage. Soapy sprays can be used but, since you need a direct hit, tend not to be very effective. The remaining alternative is to use commercial insecticides (University of Minnesota Extension Office). (We used the thumb and forefinger technique.)