Black-margined aphids create sticky leaves

   This week, I noticed the appearance droplets of sticky sap spotting the leaves of our pecan trees (photo at right). In fact, when standing in the shade of one of our pecan trees, I could feel tiny droplets of plant sap hit my arms and face. It seems we have begun our annual outbreak of pecan aphids and they are covering the tree and everything under the tree's canopy with honeydew.   

     I pulled a few leaves off a tree to look for aphids.  What I found were numerous adults and nymphs. In the photo at left, note that only the adult aphids have wings. The black markings on the outer edge of each wing identifies this insect as a black-margined aphid. The wing-less insects represent immature stages of aphids call nymphs. Note in the photo that there are several sizes of nymphs. Young aphids molt their exoskeletons as they grow larger leaving behind white cast skins on the underside of leaves. There is one cast skin in the photo, can you find it? (upper center of photo).
    Rain is forecast for this weekend and a heavy rainstorm can often cause a dramatic drop in aphid populations. If we do receive significant rain, we will need to spray for pecan weevil next week and if aphid populations persist we probably add an aphicide to our weevil spray.