Griswold — Hanging from a pole in a mixed evergreen woodland, the odd-looking device yielded a haul of a hundred or so tan-and-orange beetles, some no larger than a pinhead and others the size of a grain of rice.

The trap, a chain of pheromone-laced funnels that empty into a single receptacle, had been luring beetles since scientists at the Connecticut Agricultural Experiment Station set it up at the research farm here in Griswold on May 1, one of six trap sites around the state.

On Friday, Claire Rutledge, assistant agricultural scientist with the experiment station, and Mioara Scott, summer research assistant, came to collect the specimens in a Ziploc bag to bring back to the lab in New Haven.

“Are they southern pine beetles?” Rutledge asked, examining the contents of the bag. “We need to get them under a microscope to tell. Overall, we’re trying to figure out how widely dispersed they are in Connecticut, and whether the numbers are at endemic, low levels, or at epidemic levels.”

Since the beetles were first detected in Wallingford in March, the experiment station has confirmed their presence in multiple locations around the state, including on Coit Lane in Norwich, where the infestation killed a red pine. The beetles have been moving gradually north for decades, Rutledge said, appearing in the Pine Barrens in New Jersey about 10 years ago and on Long Island in October.

“Now we’ve found them in lots of disparate locations around the state,” she said. “It’s been really patchy where we find them. The way these guys operate is that they’re mass attackers. The trees die over the course of about two years.”

Thus far, she said, the beetles haven’t been found in the first few specimens collected from the Griswold site, but traps at the other five sites — from the northwest corner to New Haven County — all caught some of the destructive beetles.

They primarily attack three types of evergreen — red pine, Scots pine and pitch pine — but have also attacked Norway spruce. Of these, pitch pine — the only native species of the four — is at the greatest risk, Rutledge said. White pine, the most predominant evergreen in Connecticut, is not susceptible.

“Ecologically, pitch pine is the tree of biggest concern,” she said. Pitch pine forests, she added, maintain a habitat important to bird species, including the whippoorwill, and 11 species of spiders.

A tree under attack by the beetles will bleed yellow "popcorn" resin onto its bark in an attempt to smother the insects. Once they successfully burrow inside the tree, the females dig tunnels, where they lay eggs. But what really kills the tree, Rutledge said, is the fungus carried by the beetles that turns the wood a bluish-black.

“This is what a successful infestation looks like,” she said, showing a slice of bark from an infested red pine cut down in Hamden, riddled with tunnels and blue-black streaks.

Last week, Rutledge said, the beetles were found in central Massachusetts. One of the main questions she and other scientists want to answer, she said, is whether the beetles have adapted to New England winters, or are getting carried north by winds in the spring. In New Jersey, she said, the beetles enter a dormant phase during the winter months, a behavior they don’t exhibit in their native territory in the South.

“If they survived this past winter, they can survive any winter,” she said.

Once an infestation takes hold, she said, there is no cure. There are preventive insecticide treatments, though, including dinotefuran and bifenthrin, but she’d prefer these be used sparingly if at all. Instead, she advocates people keep their trees as healthy as possible, giving them the best chance of using their own defenses successfully.

“They can gain a foothold on weak trees,” she said.

Anyone who sees trees they believe are infested with southern pine beetles is asked to call Rutledge at (203) 974-8484 or send an email message to: ctstateentomologist@ct.gov.

“Since mid-April, we’ve gotten a fair number of calls from people who had it,” she said. “We’ve collected specimens from 10 or so new locations. It’s been helpful to have people look for it.”

j.benson@theday.com

Twitter: @BensonJudy