Keeping insects from peach trees includes a spraying schedule that begins during the winter. According to Utah State University, multiple applications of pesticide may be warranted during the growing season. Many species of peach tree borers invade not only the fruit but the tree trunk as well. Without treatment through spray applications the bugs will damage or kill the fruit-bearing tree.
Apply a dormant oil spray to the peach tree prior to bud swell of the peach blossoms. Mix the refined oil according to label directions.
Coat all surfaces of the tree limbs and trunk. Spray the tree in early morning when temperatures are above freezing. The dormant oil spray will suffocate any eggs laid on the tree bark and in crevices of the trunk.
Check the peach tree for insect activity as the peaches begin to form. Peach twig borers will begin activity from June until September during the fruit formation and ripening. Effective insecticides include phosmet, diazinon and methoxychlor. Follow label directions for application rates and frequency. Repeat applications during the season. Excessive rainfall will create more opportunities for the insects and repeated sprayings will be required.
Inspect the lower trunk areas of the peach trees. Signs of oozing sap and small piles of sawdust indicate the presence of peach tree borer.
Apply the insecticide endosulfan to the trunk area only. Avoid contact of the chemical with upper limbs and fruit of the tree. Follow mixing instructions on the chemical label. According to Utah State University, endosulfan is the recommended insecticide for effective control of the borer's eggs and larvae.