Millions of small, white butterflies have been fluttering around forests and yards in many areas of the state this summer, a phenomenon not often seen in Idaho.
Central and Southern Idaho, and Central Oregon are enduring a pine white butterfly outbreak, which only happens every 30 to 50 years, according to U-S Forest Service entomologist Dayle Bennett.
The butterflies themselves are harmless, but the eggs they’re laying inside pine and fir tree needles will hatch caterpillars next spring that can defoliate trees. Bennett says affected pines may look a bit odd, yet most will survive.
USFS entomologst Dayle Bennett comments on the butterfly’s eating habits.
Bennett says pine white butterflies are always present, but usually not in such large numbers. And even when there is an outbreak, experts don’t know if it’s a guarantee of trouble. Bennett saw swarms of pine whites north of Boise in the mid-1990s.
Bennet talks about the outbreak he has seen.
Pine white butterflies are native insects that have co-evolved with pines, and they naturally die out after a couple of years. The Forest Service has no plans to take action, since effective insecticides would do more harm than good.
Some property owners may be concerned about landscape tree health, and Bennett says they should contact a local extension office for information about possible control methods.
