The beetles can over-winter in any life stage: egg, larval, pupal, or adult, and produce three to seven generations a year. In New Jersey, the northern-most range of southern pine beetle, beetles usually overwinter in the the pupal stage and produce around two generations per year.
A pair of beetles bore galleries into the tree’s inner bark for the female to deposit eggs. The eggs hatch into larvae, which feed on the tree’s bark. The larvae then become non-feeding pupae, and finally adult beetles. The adults exit the host tree and fly, sometimes several miles, to a new tree.
The “S” shape of the galleries distinguishes this beetle from others. Galleries are created by the larval stage of the insect as it devours the tree’s critical inner bark. These galleries girdle the tree while the beetles transmit blue-stain fungi. The fungi stop water from circulating within the tree. The girdling and fungus may kill the tree within two months after the initial attack.