An insect called twig girdler is probably responsible for the damage. The female twig girdler lays her eggs in the twigs of many kinds of trees, like maple, oak and pecan. After she has finished laying her eggs she then chews the twig off so it drops to the ground where the life cycle of the insect will be completed. The only control measure to take is to rake up the fallen twigs and dispose of them. This disrupts the life cycle of the twig girdler and reduces the numbers of them in the next generation