CARY -- Hemlock Bluffs Nature Preserve and Stevens Nature Center reopened Wednesday after combating an outbreak of tiny insects that threatened a group of trees in the 158-acre park.

The park opened ahead of schedule, thanks to cooperative weather that allowed contractors to quickly rid the preserve of the hemlock woolly adelgid, an an aggressive aphid-like insect that is native to Asia.

The bugs were found this summer in 11 of the preserve's 235 Eastern hemlock trees and could've wiped out the entire population.

The town used a "bark painting" treatment on all of the trees in the preserve on Monday. The insecticide directly applied to the bark is harmless to the tree, according to Doug McRainey, the town's parks planning manager.

The method should save the 11 affected trees, McRainey said. Bartlett Tree Experts, a tree care company, will be paid about $13,500 for the treatment.

The contractors will check the trees again in October to evaluate their condition and check for any new adelgid activity.

The Eastern hemlocks in the Hemlock Bluffs Nature Preserve grow along north-facing bluffs above Swift Creek, far from their normal range in the foothills and mountains of North Carolina. The state owns most of the land in the preserve, which is operated by the town and draws about 100,000 visitors a year.