Dead ants form a dark line on the bay beach in South Jamesport Sept. 12. Courtesy photo: Joan Cear.

A strange phenomenon occurred in South Jamesport last week: thousands of dead ants washed ashore en masse.

Jamesport resident Joan Cear snapped some photos of a tide line of dead ants on the shore of the town beach in Jamesport on Sept. 12 and 16.

What happened and why the dead ants washed ashore like that is something state environmental officials don’t have a clear answer for.

Thousands of dead ants washed ashore at the town beach in South Jamesport Sept. 12. Courtesy photo: Joan Cear.

“DEC cannot definitively conclude why this incident occurred. Unusually large numbers of flying ants have been observed in recent weeks throughout the region. These ants are not strong fliers, and many times may fly over water, drown, and wash up on the beach,” the agency said in a statement. “Alternatively, recent heavy rains may have washed out a large nest. This may be less likely due to the absence of pupa and eggs in the wash up.”

The DEC does not believe this event is related to pesticides or chemicals as the incident is focused on one species of insect, an agency spokesperson said in an email. “A contaminant would likely affect an array of species.”

A Cornell Cooperative Extension entomologist also could not provide a definitive answer.

“Very interesting,” entomologist Dan Gilrein said after reviewing photos taken by Cean.

”I am not sure why, but it might be associated with the heavy rains parts of the north shore just received. There was an isolated heavy downpour in a fairly small area (Riverhead to Southold I think) maybe a week ago that could be responsible, perhaps, by washing out some colonies or possibly workers active on the surface,” he wrote in an email today. “These look like workers that would never have been able to fly. (eggs/larvae may have quickly disappeared or been consumed),” he said.

“My suspicion is these may be pavement ants, Tetramorium caespitosum, which are very common here. Sometimes colonies can get flooded, driving out the workers at least temporarily.”

Gilrein said he heard of recent reports of of winged ant flights. Some species are known to have synchronized flights in late summer and fall, he said.

“I had more than a few calls/inquiries about the flights from all around Suffolk and into Nassau, happening about the same time (4 to 5 p.m. or so) on Sept. 12 he said.

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Denise is a veteran local reporter, editor, attorney and former Riverhead Town councilwoman. Her work has been recognized with numerous awards, including investigative reporting and writer of the year awards from the N.Y. Press Association. She is a founder, owner and co-publisher of this website.Email Denise.