Week 36 – Sept 7 – 10

2010 Mosquito Report: Week 36

Report based on data collected from traps deployed the week of September 7, 2010 through September 10, 2010. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Host-seeking mosquito activity has increased throughout most of Norfolk County along areas prone to flooding. The increase in activity has been noted in the towns of Canton, Dedham, Holbrook, Medfield, Medway, Milton, Needham, Walpole, and Weymouth. Activity has remained average in Foxboro, Franklin, Millis, Norfolk, Quincy, and Wrentham whereas a decline in activity was reported in Bellingham, Plainville, and Sharon.

Gravid Traps:
A few towns experienced higher than average gravid mosquito activity such as Dover, Norwood, Stoughton, and Weymouth. Most towns reported only average levels of gravid mosquito activity whereas the following towns reported a decline in activity: Avon, Braintree, Canton, Holbrook, Millis, Milton, andNeedham.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC-trapped mosquito in Norfolk County this week is Aedes vexans due to heavy rain events from a couple of weeks ago. Ochlerotatus trivittatus populations are higher than average in Weymouth and so is a population of Psorophora ferox in Canton.

Gravid Traps:
Culex pipiens/restuans populations are average to lower than average throughout most of Norfolk County. Ochlerotatus japonicus numbers are average.

3. Comparison to previous season

Host-seeking mosquito activity continues to be low into this week. Higher than average host-seeking activity reported in the above towns is primarily due to a recent emergence of Ae. vexans due to the last heavy rain event which affected mostly the eastern portion of the county. WNv is still being isolated withinNorfolk County with Quincy and Westwood being the latest towns reporting positive mosquito pools. Until the first frost, caution should be practiced when partaking in outdoor activities in the form of protective clothing and/or insect repellant.

4. Weather Summary

This week was mainly dry and much cooler than previous weeks. A brief warm-up at mid week was followed by a strong cold front that brought below normal temperatures for the end of the week. The front brought widespread thunderstorms on Wednesday morning; however, rainfall amounts were fairly light. Most areas received between a tenth and quarter inch of rain, highest amounts in the far north, and lowest amounts (less than a tenth of an inch) across the center of the county.

Total weekly rainfall: 0.04 inches (-0.77 in.)
Total Monthly rainfall: 0.59 inches (-0.67 in.)
Total Yearly rainfall: 36.21 inches (+7.25 in.)

5. Number of requests for service

NCMCP received 7,148 calls year to date for service as of 9/10/10. NCMCP received 194 calls for service this week.

6. MCP/Commission response

NCMCP suspended all ground ULV applications effective Friday, September 10, 2010 due to the long range prediction of low (fall like) temperatures during the overnight hours. NCMCP stands ready to resume these adult control operations if conditions warrant it and weather permits. Overall complaints from residents (year to date) has hit a new record for the Project at 7,148. The next highest year was 2006 where NCMPC received 7,085 calls for the season. NCMCP has also suspended all rain basin treatments having treated the rain basins in most of the highly urban areas across the county. NCMCP dispatched field personnel to treat the salt marshes following the monthly high tides. Some rain induced larval development was also treated in these marshes as well as in Broad Meadow. WNV activity continues along the eastern edge of the county as virus has now been isolated in mosquitoes collected in Dedham, Norwood, Quincy and Westwood. Public outreach continues in the areas of positive collections. NCMCP will continue to operate gravid traps and light traps on a weekly basis until collections drop off. This drop off usual occurs by the end of September. The Director notes that although virus activity persists, the Project transitions from considering a control strategy to public outreach. As weather conditions deteriorate adult control operations become ineffective so it is important to continue promoting personnel protection whether that be the use of an appropriate repellant, avoiding activities from dusk till dawn or wearing long sleeved shirts and pants when outdoors in mosquito active areas. These personnel protection efforts should continue until the first hard frost of the fall.


144 Production Rd, Suite C

Walpole, MA 02081

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