Week 37 Sept 13 – 17

2010 Mosquito Report: Week 37

Report based on data collected from traps deployed the week of September 13, 2010 through September 17, 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 returned to normal levels throughout most of Norfolk County. Only the towns of Canton, Dedham, Milton, and Weymouthshowed in an increase in host-seeking mosquito activity (primarily due to late season Ae. vexans emergence) whereas Holbrook, Medway, Plainville, Quincy,Sharon, and Wrentham reported a decline.

Gravid Traps:
Most towns throughout Norfolk County reported average levels of gravid mosquito activity. Only Dedham, Medway, and Stoughton reported higher than average levels of gravid mosquito activity whereas Avon, Franklin, Millis, Needham, and Westwood reported a decline from the average.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC-trapped mosquito in Norfolk County this week is once again Aedes vexans due to heavy rain events from a few weeks ago. The cooler temperatures have already brought down their populations in comparison to last week’s collections.

Gravid Traps:
Culex pipiens/restuans populations are average to lower than average throughout most of Norfolk County. Ochlerotatus japonicus appears more populous in cooler weather but all indications point to average levels of activity.

3. Comparison to previous season

Host-seeking mosquito activity continues to be low to average for 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 inMassachusetts (with Quincy and Westwood being the latest towns in Norfolk County 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 started mainly dry with cool temperatures. A low pressure and its associated fronts brought rain to the area Thursday night into early Friday. Amounts were generally from ¼ to ¾ of an inch county-wide, with highest amounts in the south. So far this month, the entire county has had below normal rainfall (25-50% of normal), while 30-day rainfall has been above normal, (except in the far west), and 60-day rainfall has been near to slightly below normal county-wide. With the exception of Tuesday, temperatures were slightly below normal all week.

Total weekly rainfall: 0.52 inches (-0.28 in.)
Total Monthly rainfall: 1.11 inches (-0.95 in.)
Total Yearly rainfall: 36.73 inches (+6.96 in.)

5. Number of requests for service

NCMCP received 7,216 calls year to date for service as of 9/17/10. NCMCP received 68 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 temperatures during the overnight hours. NCMCP stands ready to resume these adult control operations if conditions warrant it and weather permits. NCMCP has also suspended all rain basin treatments having treated the rain basins in most of the highly urban areas across the county. Water management is now the main focus of field operations. 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. No new virus isolates were indentified in trap collections this week. The Director notes that although virus activity persists, the Project has transitioned from considering a control strategy to public outreach. As weather conditions continue to deteriorate adult control operations become ineffective so it is important to continue promoting personnel protection whether thatbe the use of an appropriate repellant, avoiding activities from dust to 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