Week 37 – Sept 10 – 11

2008 Mosquito Report: Week 37

Report based on data collected from traps deployed on Wednesday, September 10, 2008 and retrieved on Thursday, September 11, 2008. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
In general, mosquito activity in CDC traps continues to decline across the county due, in a great part, to cooler evening temperatures but there is also, no doubt, a natural decline in the populations occurring.

Gravid Traps:
In general, mosquito activity in gravid traps continues to decline across the county due, in a great part, to cooler evening temperatures but also as a reflection of a natural decline in the Culex populations.

2. Current Predominant Species

Ochlerotatus canadensis is the most predominant species this week. The numbers of Aedes vexans continue to drop. Gravid traps are dominated by Culex pipiens/restuans. Ochlerotatus japonicus populations remain at low levels.

3. Comparison to previous season

In contrast to the previous weeks’ high activity compared to last season, CDC and gravid trap activity are finally on par with last season, with a few towns showing even less mosquito activity. NCMCP anticipates an increase in reflood species, especially Aedes vexans, as a result of heavy rains which fell a while ago associated with tropical system Hanna. This may not be reflected in the CDC traps due to cooler trap night temperatures.

4. Weather Summary

There were two periods of rain this week. The first was a line of heavy showers and thunderstorms with a cold frontal passage on Tuesday. This produced a quick widespread ¼ to ½ inch of rain across the county. On Friday evening, a warm front produced a period of light rain that brought between a tenth to a third of an inch county-wide. Weekly totals were between ½ to ¾ of an inch county wide which is near normal. Temperatures were near to slightly below normal.

Total weekly rainfall: 0.59 inches (-0.10 in.)
Total Monthly rainfall: 3.11 inches (+1.62 in.)
Total Yearly rainfall: 36.12 inches (+6.93 in.)

5. Number of requests for service

Year to date NCMCP has received 4,398 calls for service as of 9/12/08. This represents a total of 208 calls for the week. Numbers of calls went up significantly this week most likely due to media coverage of recent positive West Nile virus mosquito pools in Dedham, Holbrook, Weymouth and Westwood.

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

Office: (781) 762-3681
Fax: (781) 769-6436