Wednesday, May 14, 2014

All About Ticks

The Deer Committee welcomed guest speaker Kirby Stafford from the Connecticut Agricultural Experiment Station to get a better understanding of tick-borne diseases in Connecticut, and the role that deer play in the disease rates.

The focus was on Lyme Disease, although there are several other illnesses transmitted by the Deer Tick (aka Black Legged Tick).  Mr. Stafford noted that evidence of Lyme Disease was detected in the 5,000-year-old "Ice Man."  In the 1800's, when New England was cleared for agriculture and deer nearly eradicated, ticks became very rare except in some isolated areas, such as the tip of Long Island and some islands. There was an ailment at the time called "Montauk's Knee" or "Montauk Spider Bite," that was probably Lyme Disease.

Opponents of deer control will often point out that ticks do not pick up Lyme Disease from deer, which is true.  The disease is acquired from other animals, usually mice, chipmunks, and certain species of birds. 

However, ticks do need a certain deer density to reproduce and lay eggs.  Adult ticks must feed on a large mammal, usually a deer, before they can reproduce. How many deer are needed? Mr. Stafford said the various studies and computer simulations all seemed to point to a density threshold of 8-12 deer per square mile at which the tick population (and Lyme Disease rates) significantly falls. Recreational hunting in the suburbs can only bring deer down to about 30 deer per square mile. Although recreational hunting can significantly improve forest ecology, and reduce landscaping damage and vehicular accidents, any impact in Lyme Disease rates would probably be modest. In order for deer control to seriously reduce the incident of Lyme Disease, "controlled hunts" (professional sharpshooting) need to be implemented in order to reduce the number of deer to 8-12 deer per square mile.

In Redding, a study is underway that involves significant deer reduction within a couple one-mile plots.  Interestingly, it was hunters who protested the sharpshooting study rather than animal-rights groups.

The tick-epidemic has resulted in many families "treating" their yards for ticks. The Deer Committee heard about some yard tick treatments that are both effective and environmentally-friendly, including the use of bait boxes for mice. There are no yard sprays that kill only ticks. Most sprays currently used are pyrethrin or pyrethroid-based, and these target all insects (including good insects) and are toxic to aquatic wildlife. Mice go into baitboxes for a treat and rub up against some insecticide that kills any ticks they may be carrying.   There is a biocide spray that consists of a naturally-occurring fungus that is effective. This spray does kill some other types of insects but not most beneficial species.