Wednesday, August 3, 2011

Serpentine leafminer

    Sometimes when I walk through our grove I'll spot one of the many minor pests of pecan. This time its was the serpentine leaf miner (photo at left). What looks like a white worm on the surface of a leaflet is actually a tunnel made by the larvae of  Stigmella junglandifoliella. This very small larvae feeds on leaf tissue just below the epidermis of the leaf. In the photo, you can see that the larvae hatched near the tip of the leaflet and started to tunnel up along the left side. Note that the tunnel gets wider as the larvae grows in size. Eventually the larvae will pupate in the tunnel. A short while later, a small, purple and white moth, measuring only 1/8 inch in length,will emerge, break through epidermis of the leaf  and start a new generation of leaf miners.  This insect can have 4-5 generations per year. Control measures are necessary only in rare outbreak situations.