Week 39 – Sept 24 – 25

2008 Mosquito Report: Week 39

Report based on data collected from traps deployed on Wednesday, September 24, 2008 and retrieved on Thursday, September 25, 2008. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Although there are higher than usual numbers of Aedes vexans in the towns of Canton, Milton, and Plainville, CDC mosquito activity remains mostly the same with low numbers across the county.

Gravid Traps:
Gravid trap activity is reflecting a substantial drop in mosquito activity compared with last week’s higher than average numbers. Trap counts are lower this week especially in the towns of Avon, Bellingham, Canton, Dedham, Dover, Franklin, Holbrook, Medway, Millis, Milton, Needham, Norwood, Plainville, Quincy, Randolph, Walpole, and Westwood.

2. Current Predominant Species

The most predominant mosquito species in CDC traps are Aedes vexans with populations that spiked in the above towns. Ochlerotatus canadensispopulations are declining. Gravid traps are dominated by Cx. pipiens/restuans still. Ochlerotatus japonicus populations have climbed in a few towns, especially in gravid traps with few Cx. pipiens/restuans.

3. Comparison to previous season

In general, CDC activity this week is the same this season compared to last season except for Canton, Milton, and Plainville due to unusually higher than average Aedes vexans populations. Gravid trap mosquito activity this week is generally the same as last season’s numbers but there is significantly lower activity in Avon, Bellingham, Canton, Dedham, Dover, Franklin, Holbrook, Medway, Millis, Milton, Needham, Norwood, Plainville, Quincy, Randolph, Walpole, and Westwood. Of note is the trend towards cooler evening/morning temperatures which will no doubt affect trap collections.

4. Weather Summary

This week was mostly dry until the end of the week when a tropical moisture feed set up across southern New England bringing periods of heavy rainfall Friday through Sunday. Three-day rainfall totals averaged 2-4 inches across the county. While this rainfall did not cause any significant flooding on our flood plains, soil conditions were already moist from prior rains. This rainfall likely re-charged area wetlands as water tables were brought close to the surface. Over the past 30, 60, and 90 days, rainfall totals are running between 125% – 200% of normal county-wide. Temperatures throughout this week averaged slightly below normal. Below are 3-day rainfall amounts from across the county, courtesy of spotter observations to the National Weather Service in Taunton.

Total weekly rainfall: 3.59 inches (+2.77 in.)
Total Monthly rainfall: 7.13 inches (+3.90 in.)
Total Yearly rainfall: 40.14 inches (+9.20 in.)

5. Number of requests for service

NCMCP has discontinued the recording of calls for early morning ULV applications.

6. MCP/Commission response

NCMCP has discontinued “area wide” ground ULV applications effective Friday, September 12, 2008 due to predicted long range weather conditions that will not be conducive to effective applications. Coordination between NCMCP and the local Boards of Health is ongoing relative to interpretation of surveillance results and how best to get the word out to the public relative to avoidance of mosquito bites. NCMCP remains prepared to conduct additional ground adulticide activities if required.


144 Production Rd, Suite C

Walpole, MA 02081

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