There was good news in Shelter Island’s battle to control ticks and the illnesses they spread.
In samples taken at 10 locations on the Island in June, the numbers of a particular category of ticks — Lone star nymphs — have remained down significantly since 4-poster units were deployed on the Island seven years ago.
Four-posters are units placed in fields and woods that are baited with corn. As deer feed, their necks are coated with the tickicide permethrin.
First introduced on the Island in 2008, when 60 units were deployed, there has been a steady drop in the recorded numbers of Lone Star Nymphs. An average sampling at 10 sites tested in 2008 reported 440, and tests done last month at the same 10 sites recorded an average of 50 Lone star nymphs.
There are currently 32 4-posters deployed.
Even though there was a bump from an average of 31 insects recorded last June, this year’s test results is “encouraging news,” according to Mike Scheibel, chairman of the town’s Deer & Tick Committee and Mashomack Preserve’s natural resources manager.
Mr. Scheibel conducted four of the 10 tests in Mashomack, and Highway Department employee Nick Ryan, who manages the 4-poster program on town-owned property, did the remaining tests.
The method used is called a “tick drag,” where a large white cloth of corduroy-like material is dragged across sites and the ticks are then counted that cling to the material.
In 2008, the first year 4-posters were deployed, sample sites averaged 440 Lone Star nymphs. After two years of sampling from the same sites and using the same methods of testing, the average was down to 18.
With the scaling back of 4-posters by almost half in recent years, the numbers of ticks recorded has risen and fallen, to a high of 84 in 2013. That number fell to 31 the following summer.
It’s worth noting, Mr. Scheibel said, “that we are not seeing the same results obtained after three years of full — 60 units — deployment, but nevertheless, a significant change since the days prior to the 4-poster [program].
Average numbers, Mr. Scheibel added, since 2008 have been eight or nine times less, “which is significant.”
Mr. Scheibel said there has also been “a modest reduction in deer density since 2008,” which could be a factor in fewer Lone Star nymphs being recorded. Changing environmental conditions may also have affected the insect population.
“But whatever we’re doing, it does seem that the results are trending in the right direction,” Mr. Scheibel said.