Jack Pine Budworm in Ontario (Choristoneura pinus pinus Freeman)

Background

Jack Pine Budworm is the most serious insect affecting jack pine in Ontario.

Jack Pine Budworm is a native insect that periodically reaches outbreak levels (approximately every 8-10 years) in Ontario. The budworm larvae cause widespread defoliation, growth loss, top kill and tree mortality. Jack pine is the preferred host. Other conifers such as eastern white pine, red pine and Scots pine can be attacked, especially when growing in association with jack pine.

What does it do?

• Larvae (caterpillars) feed on the needles and male flowers.
• Attacked trees turn reddish-brown in June and July from the partly-chewed drying needles. Larval droppings and partially-chewed needles get caught in silk spun by larvae on the twigs.
• Defoliation can lead to widespread discolouration and browning of foliage throughout the forest.
• All the needles in the upper crown may be consumed, while some foliage may remain in part of the tree.

Life Cycle of the Jack Pine Budworm

1. Tiny larvae emerge from under the bark in late May or early June and begin feeding on the pollen in male flowers and then move on to developing needles of the new shoots.
2. The majority of the feeding is done in later larval stages (late June and early July). The mature larva is 21mm long, has a reddish-brown head, a reddish-brown body with yellowish sides and two rows of white dots on its back.
3. Pupation occurs on the shoot in July or early August.
4. The tawny brown moth with a wing-span of 15-24 mm emerges in July or early August.
5. Eggs are laid on needles in clusters of two or three overlapping rows, with approximately 40 eggs per mass. Within 10 days the eggs hatch and the tiny larvae find protected areas under the bark where they spend the winter.

Images provided by the Ontario Ministry of Natural Resources and the Canadian Forest Service.