Week 37 – Sept 9 – 10

2009 Mosquito Report: Week 37

Report based on data collected from traps deployed on Wednesday, September 9, 2009 and retrieved on Thursday, September 10, 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 this week was mostly lower than average to average across Norfolk County. The only town reporting higher than average mosquito activity was Quincy. Avon, Braintree, Canton, Dedham, Foxboro, Millis, Milton, Needham, Norfolk, and Plainville reported average levels of mosquito activity. The towns of Bellingham, Holbrook, Franklin, Medfield, Medway, Sharon, Walpole, Weymouth, and Wrentham experienced lower than average mosquito activity.

Gravid Traps:
Most gravid traps have once again dropped below average levels of activity across Norfolk County. No towns reported higher than average gravid mosquito activity. The following towns experienced average mosquito activity: Foxboro, Dover, Medfield, Norfolk, Quincy, Walpole, and Weymouth. The remaining towns collected lower than average gravid mosquitoes.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC trapped mosquitoes in Norfolk County this week were Culex pipiens/restuans, but their numbers are dwindling with only localized populations remaining. Ochlerotatus sollicitans and Oc. cantator are plentiful in Quincy.

Gravid Traps:
Although gravid traps remain predominated by Culex pipiens/restuans, their abundance has dropped significantly from the average level of mosquito activity.

3. Comparison to previous season

Compared to the previous seasons, host-seeking mosquito activity this week was mixed. Culex pipiens/restuans populations have dipped throughout the county, but remain higher than average once again in Quincy. There was only a localized occurrence of abundant Ochlerotatus sollicitans and Oc.cantator in Quincy. Gravid trap activity has dropped once again throughout Norfolk County. The weather has been very cool lately which may be contributing to the lower collection.

4. Weather Summary

Temperatures this week were near to slightly below normal with no precipitation to start the week. A slow moving storm system produced a significant rainfall event at the end of the week. Three day totals for this storm ranged from around an inch in western sections to over three inches in the extreme eastern sections. Due to the previous dry conditions, this rainfall was not enough to create any significant flooding on our rivers. Over the longer term, 14 and 30-day rainfall has been well below normal in the west and a bit above normal in the east, while 60, 90, and 180 day rainfall has been above normal county-wide.

Total weekly rainfall: 1.72 inches (+0.80 in.)
Total Monthly rainfall: 1.72 inches (+0.23 in.)
Total Yearly rainfall: 31.93 inches (+2.74 in.)

5. Number of requests for service

NCMCP received 5,762 calls for service as of 9/11/09. NCMCP received 97 calls for service this week.

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. NCMCP remains prepared to ULV areas if high level virus activity is identified anywhere in the county. Declining, but still moderate, populations of Oc. sollicitans and Oc. cantator continue to plague areas of Quincy adjacent to Broad Meadow and North Weymouth in the Neck Street area. Both of these are as a result of man made disturbances. 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. NCMCP remains prepared to conduct additional ground adulticide, ground larvicide and aerial larvicidecontrol activities as required.


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