Comment on the Lemon Fair Insect Control District NOI

The two insect control districts in Vermont have submitted requests to continue their operations for the next five years. This request is referred to as a Notice of Intent (NOI) to apply pesticides according to Vermont’s Pesticide General Permit (PGP). The two districts are the Brandon-Leicester-Salisbury-Goshen-Pittsford Insect Control District (BLSG) and the Lemon Fair Insect Control District (LFICD) which includes Bridport, Cornwall, and Weybridge. The Vermont Department of Environmental Conservation (DEC) will make a decision about both NOIs very soon.

The Lemon Fair NOI was submitted recently and the public comment period is open until May 14. The LFICD controls mosquito larvae using the same bacterial larvicides as the BLSG. Unlike the BLSG, the LFICD does not also use methoprene, an insect growth regulator, to kill larvae. The LFICD does not do any roadside spraying of chemical pesticides (adulticides) to kill adult mosquitoes, while the BLSG has an extensive program of roadside spraying of permethrin and malathion to kill adult mosquitos.

We submitted a comment to the DEC and included six points which are summarized below. We are impressed with the LFICD’s plan to control mosquitoes without chemical pesticides. The LFICD confronts essentially the same mosquito problem as the BLSG, but unlike BLSG, LFICD recognizes that the environmental and health risks associated with pesticides like methoprene,  permethrin, and malathion might be more serious than the nuisance of some additional biting mosquitoes.

An outstanding question is: Can DEC approve two radically different plans to address the same mosquito problem?

1. The LFICD’s NOI correctly identifies its objective as controlling nuisance mosquitoes—not vector mosquitoes.

While recognizing that mosquitoes are potential vectors of arboviruses, the LFICD NOI does not attempt to justify its work with reference to serious, but locally rare diseases. In contrast, the BLSG’s NOI—currently pending review by DEC—frequently mentions mosquito borne illnesses, including some diseases that do not occur in Vermont, as their primary rationale for pesticide application.

According to Vermont Mosquito Control statutes, the jurisdiction to control vector mosquitoes lies with the Department of Health—not the BLSG or LFICD[1]. The Agency of Agriculture and Food Markets classifies the BLSG and LFICD as “nuisance” mosquito control districts.[2]

2. The District’s NOI is consistent with the intent of the Pesticide General Permit.

The LFICD’s philosophy and approach toward nuisance mosquito control is consistent with Vermont’s 2017 PGP and Integrated Pest Management (IPM). The PGP specifies that Operators should minimize the discharge of pesticides to waters of the State.[3] To accomplish this Operators are required to use Pest Management Measures, along with developing Action Thresholds, and a Pesticide Discharge Management Plan (PDMP), which deploys a Pest Management Options Evaluation—clearly specifying that pesticides are only to be used “if all other methods are unreasonable and have been exhausted.”[4]  In this case, the LFICD’s approach and practices demonstrate their efforts to minimize discharges of pesticides to surrounding waters. Specifically, the LFICD does not use chemical pesticides—unlike the neighboring BLSG. Rather, the LFICD uses only non-harmful bacterial larvicides.

3. The District’s Pesticide Discharge Management Plan is complete and well-structured.

The LFICD’s Pesticide Discharge Management Plan (PDMP), provided within their NOI, is well-structured, complete, and thorough. In particular, the PDMP accurately identifies a description of the Pest Management Area; the PDMP Team; Pest Problem Description—citing to nuisance mosquitoes, not vector mosquitoes; robust and detailed Action Thresholds; a Pest Management Options Evaluation; along with response procedures. Moreover, the provided Addendum regarding the District’s Action Thresholds in their PDMP fills in any gray areas that might arise upon reviewing the PDMP. But again, following a common theme throughout this comment, the LFICD’s PDMP stands in stark contrast to the BLSG’s PDMP that is currently under review.

4. The District’s Action Thresholds are robust and supported by sound data.

The synopsis provided in their Action Threshold addendum within the NOI demonstrates thoughtful consideration, context, and accuracy in developing a sound Action Threshold for biological larvicide application. Moreover, LFICD specifies that there must be over 10 dips representing a 200 acre area in order for the Action Threshold for larvicide application to be met. LFICD provided a thoughtful and complete explanation of the process and reasoning behind their action thresholds. In contrast, the BSLG’s NOI simply cited “10 per white dip cup” and “15 per trap/net sweep” with no context or justification. Not only does the LFICD include a higher Action Threshold (20 larvae per dip) for larvicide application than the BLSG (10 larvae per dip)—it’s thorough with the inclusion and requirement of over 10 dips representing a 200-acre area.

5. For the control of mosquito larvae, the District’s NOI proposes to apply bacterial larvicides, not the more widely toxic methoprene, an insect growth regulator.

The LFICD NOI specifies that they do not intend to use methoprene, an insect growth regulator, during their larvicide applications. This too, is consistent with the intent of IPM and the PGP of using the least harmful method for mosquito control. Again, this is in contrast to BLSG’s proposal in their recently submitted Notice of Intent, which outlines their intent to use methoprene without specifying how the dose will be determined—therefore leaving zero assurance that many aquatic invertebrates and vertebrates will not be harmed. Vernal pools—a critical habitat for vulnerable species (e.g., fairy shrimp, fingernail clams, amphibians)—are specifically targeted for application of methoprene in the BLSG NOI. We support the LFICD’s conservative approach to larvicide control, which poses minimal threat to wildlife.

6. The District proposes controlling nuisance mosquitoes without using harmful adulticide chemicals like malathion and permethrin.

Not only does this comply with the intent and philosophy of IPM, but it minimizes the discharge of pesticides to waters of the State of Vermont—a foundational aspect of the PGP. This approach lies in stark contrast with that of the BLSG. Specifically, mosquitoes in the LFICD region arise from same type of low-lying swamps and surrounding agricultural fields as in the BLSG. In fact, the town with the largest area of forested swamp (Cornwall Swamp) is located in the LFICD. Yet, the BLSG argues that roadside spraying of adulticides is a necessary part of their control method. We are not aware of any scientific evidence that mosquito density differs markedly between the two districts. Therefore, State’s approval of two radically different control strategies is both inconsistent and arbitrary. We applaud the past success of the LFICD in reducing mosquito populations without resorting to chemical pesticides, which have been proven to have deleterious environmental and health effects.

[1] See 6 V.S.A. §1083(6) (providing authority of the Secretary of Agriculture to issue permits “when the commissioner of health has determined that available information suggests that an imminent risk to public health exists as a result of a potential [disease] outbreak …)
[2] Mosquito Control Districts in Vermont,
[3] 2017 Vermont Pesticide General Permit, Section 3.1, Operator Responsibilities.
[4] 2017 Vermont Pesticide General Permit, Section 6.1.3, Pest Management Options Evaluation.

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