Cottonwood%20Twig%20Borer (Gypsonoma%20haimbachiana) - Larvae%20bore%20into%20newly%20developed%20shoots%2C%20killing%20shoots%20and%20causing%20irregular%20growth.%20Heavily%20injured%20trees%20become%20deformed%2C%20bushy%2C%20and%20of%20little%20value.%20This%20pest%20is%20found%20throughout%20eastern%20North%20America%20but%20is%20more%20serious%20in%20the%20South%20where%20there%20are%20multiple%20generations.%20This%20insect%20has%20from%20one%20generation%20in%20the%20North%20to%20five%20in%20the%20South.%20The%20adult%20moths%20emerge%20from%20cocoons%20in%20spring%3B%20soon%20after%20the%20females%20lay%20eggs%20singly%20or%20in%20small%20clusters%20on%20the%20upper%20leaf%20surface.%20Young%20larvae%20feed%20on%20the%20leaves%20and%20veins%20until%20they%20molt%2C%20then%20they%20move%20to%20the%20base%20of%20developing%20leaves%20and%20tunnel%20into%20the%20tender%20shoots.%20Full-grown%20larvae%20move%20down%20the%20tree%20and%20spin%20cocoons%20in%20bark%20crevices%20or%20in%20the%20litter%20under%20the%20trees.%20In%20warmer%20areas%20the%20borer%20produces%20more%20generations%2C%20and%20larvae%20of%20the%20last%20generation%20overwinter%20in%20small%20silken%20shelters%20on%20the%20shoots.%20These%20larvae%20move%20to%20new%20shoots%20in%20spring%20and%20complete%20their%20growth.