CONCORD, N.H. – The discovery of several hemlock trees infected with a harmful insect has agriculture officials scouring the state for other trees sold by the Chichester nursery where they were found this summer.

The state has been struggling for years to keep the infestations of the wooly adelgid at bay. The tiny bugs attach to the underside of branches and suck out sap, which ultimately kills the tree.

Tom Durkis, state entomologist, said that so far New Hampshire’s aggressive surveillance and quarantine policies have kept outbreaks limited to small pockets, a considerable feat given the widespread infestation in Massachusetts.

But Durkis said Thursday that last month several infested trees were discovered. The trees were part of a shipment of several hundred that had arrived from growers in Tennessee.

Durkis suspected this could be a sign of a bigger problem. But by then about 300 already had been sold. Now, Durkis, his four inspectors in the state Division of Plant Industry are leading the hunt to find and burn those trees.

So far they have destroyed about 1,000 trees. In a typical year, they burn a couple hundred.

“We’re not done. We still have about 60 locations to check that we know received stock that could be potentially infested,” he said. “That’s really straining our workers.”

Durkis said his office is seeking emergency funding to help with the fight. He said his division simply isn’t equipped to handle the intensity of the searches.