"They are unbelievably numerous this year," said Allen Barlow, an aquatic biologist and author of the "Field Guide to Dragonflies and Damselflies of New Jersey." "You have two very specialized species there on the South Jersey marshes.
"The seaside dragonlet is North America's only saltwater dragonfly" that breeds in the bayside marshes, Barlow said. Those small blue-black dragonflies are in great numbers, along with the gold-orange Needham's skimmer that lives on both salt marsh and nearby freshwater ponds, he said.
The dragonflies' sweeping of the marshes helped tamp down what was an ugly greenhead season. The biting flies seemed to emerge several weeks early with the onset of 90-degree-plus days in June, said researchers at the Rutgers University marine field station, located on the Sheepshead Meadows between Little Egg Harbor and Great Bay, capitol of the greenhead kingdom.
Dragonflies are among the few predators that eat big, biting insects like greenheads and deerflies, said Barlow, who is a trustee at the Schiff Nature Preserve in Mendham and a frequent contributor to work by the state Endangered and Non-Game Species Program.
"One of the things I try to point out in my presentations and the field guide is how beneficial dragonflies really are," he said. "They consume a lot of the things that like to bite us and suck our blood and generally make summer miserable."
This summer is reminiscent of 2005, when the dragonflies made a big appearance with the end of the multiyear drought of the early 2000s. Dragonflies are creatures of the wetlands, with their breeding success in moist soils highly dependent on rainfall and weather trends.
"The dragonfly larvae are very good at going dormant," Barlow said. During bad conditions like droughts, the larvae can burrow deeper to reach still-damp sediments and wait it out. In 2005 "you were seeing accumulated years of larvae ready to come out," Barlow said. That may be what happened over the last couple of years, he added.
"Last year was the summer that didn't happen because it was so cool and rainy," Barlow said. "It may be that large numbers of dragonflies that would have emerged last year didn't."
Then early 2010s heavy snowfalls and spring rains recharged freshwater wetlands and apparently set the stage for this big dragonfly emergence, Barlow said. "That's happened all through the Northeast. You hear the same kind of reports coming in from Pennsylvania and New York and northern New England."
"I just had a Cumberland County report today, from down along the Maurice River," said Jim Bangma of Newton, who runs the website of the New Jersey Odonate Society. "Anecdotally it sounds like it is happening in a lot of places."
Some rare varieties are showing up more often too, like the red saddlebags and Scotland glider, possibly riding the winds of summer high pressure from southern states, Bangma said.
Clubtail dragonflies are all over northwest New Jersey, and Bangma said some of his sources told of seeing the unusual mustached club tail a month early.
"If you're lucky, you might see five a year. They had mass emergences around May 15," he said.
But some of Sussex County's pests showed up early too and are still hanging on, Bangma added. "Deer flies up here are still going strong and they should be almost done," he said. "I'm still getting bombed every time I'm in the woods. So go figure."