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Sebastian Zavoico ‘17.5 drags a cloth on the forest floor for a specific distance as ticks attach to it. Professor David Allen and his students use this standard method for measuring the number of ticks in an area.

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Biology Professor Says Vermont's Tick Population Has Doubled Since Last Summer

June 21, 2017


For the second year in a row, Assistant Professor of Biology David Allen and a group of students are doing tick research in Addison County during the summer. In the Q&A below, Allen discusses the variables that affect the tick population, the increase in the number of ticks, and how to guard against tick bites. Allen was also interviewed by WCAX-TV about his reseach.  

Q: What’s the focus of the research that you and some of your students are doing on ticks this summer?
DA:
The big picture question I’m interested in is: What are the landscape and ecological factors that determine tick density in Vermont? This summer we are focusing on a component of this and looking mainly at elevation and forest fragment area. Based on what is known in the literature and my understanding of tick biology, I think these two factors should be particularly important.  

Q: Where are you doing your research?
DA: We are doing this research throughout Addison County. We have 15 sites, most on Middlebury College-owned property, with about half the sites in the Champlain Valley and half in the Green Mountains.

Q: There have been reports of increases in the tick population. Is this true?
DA:
Yes. Our research shows that the numbers this year are twice as high as last year. I think there are two things going on. One is the decades-long increase in tick population numbers in Vermont. And then, separately, there are the year-to-year fluctuations in tick numbers around this steady increase. The large numbers of ticks this year compared to last probably have more to do with those annual fluctuations, which are driven by annual differences in tick host populations, includng mice and deer, and climate.

Q: What climate is favorable for ticks?
DA:
Ticks do well in wet conditions and we've had a rainy spring. Ticks also do better in warmer conditions, since their development rate is temperature-dependent. 

Q: What are some of the other interesting things you’ve learned?
DA:
One striking pattern we have seen is a drastic decrease in tick populations at 300 meters (1000 feet) elevation about sea level. Our sites below that elevation have about 15 times more ticks than those above.

(l to r) Grace Zhang ‘18, Meaghan Hickey ‘18, Ben Bormann-Winter ‘18, and Nina Job '18 take a break from their research to eat lunch.

Q: How do you and your students takeprecautions so that you don’t get any tick bites?
DA:
The students and I wear permethrin-treated coveralls. After we return from sampling, before getting back into the car, we do a visual check back and front for ticks. Then I encourage the students to shower at the end of every day we have sampled, and do a thorough check for ticks while showering.

Q: What do you recommend that people do to guard against tick bites when they are hiking or doing other outdoor activities?
DA:
I think it is important not to let the ticks keep you from enjoying the outdoors! But we do need to be more aware of them and take the proper precautions. Permethrin-treated socks and pants will help to prevent ticks from attaching or from staying on you if they do attach. It is also a good idea to spray your shoes with a DEET spray. Ticks quest from the leaf litter or short vegetation on the forest floor. For this reason, it is important to protect your feet and lower legs where they are most likely to attach. If they do attach to you, they will crawl over your body for a bit before deciding where to embed. So that is why it is important to do a thorough tick check over your entire body after you have been outside.