Trees attacked by southern pine beetles go through three stages before the beetles move on:
Fresh attacks: Females initiate the attack on the tree, releasing pheremones once a suitable host is found. Pine trees release extra resin as a defense mechanism against the beetles, though male and female beetles work together to clear away the resin and enter the bark — usually through the crevices. After southern pine beetles bore into the trees, reddish-white dust can be found on and around the tree.
Faders: S-shaped galleries are formed inside the tree, where more beetles later hatch and create new tubes. The beetle also transmits a fungus that stops water from circulating within the tree. Foliage starts to fade in color.
Vacated: Beetles born inside the tree create exit holes, allowing a mass emergence from the tree. The browning of foliage continues and bark becomes loose and peels away easily. Abundant white sawdust from the entrance and exit holes often accumulates at the base of vacated trees.
Source: Department of Environmental Conservation