Week 38 – Sept 20 – 24

2010 Mosquito Report: Week 38

Report based on data collected from traps deployed the week of September 20, 2010 through September 24, 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 is mostly average throughout Norfolk County. The towns of Avon, Canton, Franklin, Holbrook, and Weymouth had higher than average mosquito collections, whereas Medway and Sharon reported lower than average mosquito activity.

Gravid Traps:
In a rather unusual collection week, almost all gravid traps collected higher than average numbers of mosquitoes throughout the county. Only Avon, Canton, Medway, parts of Sharon, parts of Walpole, and Wrentham returned average collections.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC-trapped mosquito in Norfolk County this week is once again Aedes vexans which lingers on despite cooler conditions. A population ofAnopheles walker is higher than average in Franklin. Psorophora ferox and Ochlerotatus trivittatus is higher than average in Canton.

Gravid Traps:
Culex pipiens/restuans populations were higher than average throughout most of Norfolk County. A population of Oc. japonicus is higher than average in Medfield, but remain average throughout the rest of the county.

3. Comparison to previous season

Host-seeking mosquito activity continues to be low to average for this week although gravid collections hint at a high level of activity for Culex spp. (the primaryWNv enzootic vectors) mosquitoes with successful blood meals. Higher than average host-seeking collections 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

Not available this week.

5. Number of requests for service

NCMCP received 7,216 calls year to date for service. NCMCP had discontinued recording calls from residents requesting ULV applications.

6. MCP/Commission response

NCMCP suspended all ground ULV applications effective Friday, September 10, 2010. 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. NCMCP did experience a spike in gravid trap Culex collections which reflects an increase in activity although optimal trapping conditions no doubt contributed to the higher numbers. Lingering localized populations of the summer reflood groups are still affecting residents in some areas of the county. 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