Week 38 – Sept 15 – 16

2009 Mosquito Report: Week 38

Report based on data collected from traps deployed on Tuesday, September 15, 2009 and retrieved on Wednesday, September 16, 2009. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Host-seeking mosquito activity in Norfolk County was mixed. The following towns reported higher than average mosquito counts: Avon, Bellingham,Canton, Franklin, Holbrook, Medway, Norfolk, Plainville, Quincy, Walpole, and Wrentham. Millis and parts of Sharon reported lower than average mosquito activity, whereas the remainder of towns encountered average levels of host-seeking mosquito activity.

Gravid Traps:
Gravid mosquito activity was mixed in Norfolk County. Only the Avon, Holbrook, and Randolph traps collected higher than average mosquito numbers. Franklin, Milton, Medway, Norwood, Plainville, parts of Quincy, Stoughton, Westwood, and Weymouth experienced lower than average gravid mosquito activity. The remaining towns reported average mosquito numbers.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC trapped mosquitoes in Norfolk County this week were Culiseta melanura. Their abundance was higher than average in Avon, Bellingham, Holbrook, Medway, Plainville, and Wrentham. Culex pipiens/restuans populations have remained high in Franklin and Quincy. Psorophora ferox populations were higher than usual in Walpole.

Gravid Traps:
Although gravid traps remain predominated by Culex pipiens/restuans, their abundance has dropped significantly from the average level of mosquito activity. Ochlerotatus japonicus populations outnumber those of Culex spp. in the towns of Avon, Holbrook, and Randolph.

3. Comparison to previous season

Compared to the previous seasons, host-seeking mosquito collections in CDC traps this week were mixed. Culiseta melanura populations increased significantly in the towns of Avon, Bellingham, Holbrook, Medway, Plainville, and Wrentham. Aedes vexans and Ochlerotatus canadensis collections are low but persistent at several trap locations. The continuing cool weather has decreased our collection of gravid mosquitoes, although Ochlerotatus japonicus numbers were great in Avon, Holbrook, and Randolph.

4. Weather Summary

No rainfall reported across the county this week with temperatures near to a bit below normal.

Total weekly rainfall: 0.00 inches (+0.69 in.)
Total Monthly rainfall: 1.72 inches (-0.46 in.)
Total Yearly rainfall: 31.93 inches (+2.05 in.)

5. Number of requests for service

NCMCP has discontinued recording calls from residents requesting ULV applications effective 9/11/09.

6. MCP/Commission response

NCMCP has suspended all ULV applications effective Friday, September 11th due to consistent morning temperatures below 60 degrees and low trap counts of mammal biting species. Even with these lower counts, CDC light traps are still showing low level activity for several mammal biting mosquito species including Aedes vexans and Ochlerotatus canadensis. NCMCP plans to continue adult mosquito surveillance into early October. NCMCP remains prepared to conduct additional ground adulticide activities if high level virus activity is identified anywhere in the county subject to favorable weather conditions. Coordination between NCMCP and all local Boards of Health is ongoing relative to interpretation of surveillance data and how best to get the word out to the public relative to avoidance of mosquito bites.


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Walpole, MA 02081

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