Mild Weather Keeps Pest Numbers High
Last year’s unusual weather produced a banner crop of deer ticks in New England, and Sam Telford could not be happier. Well into last month, the researcher was still able to collect ticks - lots of them - for his studies.
“It’s not just me. I have a colleague in Rhode Island. He claims he’s been able to collect more than 15,000 ticks this fall. I am so envious. It’s like one-upmanship among us tick biologists,” Telford said from his office at Tufts University’s Cummings School of Veterinary Medicine in Grafton, where he is a professor of infectious diseases.
Based on collections at sites in Medfield, Dover, Yarmouth, Nantucket, and Martha’s Vineyard, Telford estimates that the tick population was three to five times larger than usual for early winter. He attributed the increase to last summer’s dearth of truly hot and dry weather, which usually kills a lot of ticks.
Telford’s counts involve dragging a light-colored, 1-square-meter cloth behind him as he walks through likely areas. At intervals, he stops and collects any ticks clinging to the cloth, compiling a tick-per-minute count.
“We were getting three ticks per minute at most sites, and as many as five ticks per minute,’’ he said, whereas the year before “we were lucky to get just one per minute.”
Mild temperatures well into last month also kept the ticks active later in the year than usual - a boon for scientists like Telford, but potential trouble for the unwary who do not take the same precautions in cooler months as in summer.
The population spike took place even as authorities continued efforts to curb the spread of tick-borne Lyme disease through expanded hunting of deer in towns like Dover and Medfield. A single deer can feed up to 100 adult ticks a week, with the ticks dropping off after four days of feeding and moving on to their next stage of life: laying eggs.
“Every tick that feeds can lay 2,000 eggs, so you look at places like Dover and Medfield, where they are actively trying to curb their deer populations through hunting, with all these ticks out there, the removal of one deer can prevent an awful lot of reproduction,” said Telford, who had 80 engorged adult female ticks, recently plucked off a single Nantucket deer, living in an incubator in his office.
It is too early to say whether the boom in deer ticks has been accompanied by an increase in Lyme disease cases. The state will not release its tally for last year until spring.
Reports of Lyme disease have risen for most of the past decade across Massachusetts, most dramatically in communities west of Boston. Statewide, there were 4,116 confirmed cases in 2008 and 4,061 in 2009, according to the state Department of Public Health.
But the number dropped off sharply in 2010, with 2,627 confirmed cases. Dr. Catherine Brown, state public health veterinarian, said the decline was directly related to the hot and dry summer of 2010 taking a toll on the tick population.
While Brown expects the number of Lyme cases to rise along with the tick population, Telford is not so certain.
Historically, 95 percent of new cases of Lyme disease are reported in May and June, when ticks are much smaller and harder to spot, Telford said. Just 5 percent of cases get reported in fall, when the ticks have become larger adults.
“That does not mean people should not be aware and remove the ticks, or prevent them coming on to them by using repellents, taking showers after being in the woods, and doing a tick check,’’ Telford said. “You don’t want to kick a dead skunk.”
General Manager - Staff Entomologist