Week 39 – Sept 23 – 24

2009 Mosquito Report: Week 39

Report based on data collected from traps deployed on Tuesday, September 23, 2009 and retrieved on Wednesday, September 24, 2009. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Similar to last week’s collection, host-seeking mosquito activity in Norfolk County was mixed. Most towns reported average levels of mosquito activity for this time of year. Avon, Holbrook, Medfield, Quincy, and Wrentham experienced higher than average levels of mosquito activity. The towns ofCanton, Medway, Plainville, and Sharon encountered lower than average host-seeking mosquito activity.

Gravid Traps:
Gravid trap collections this week reported lower than average to average levels of gravid mosquito activity. The towns of Avon, Dedham, Franklin, Millis, Milton, Needham, Norwood, Quincy, Randolph, Walpole, and Westwood experienced lower than average levels of mosquito activity; whereas the remainder of towns reported only average trap collection counts.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC trapped mosquitoes in Norfolk County this week were once again Culiseta melanura. Their abundance was higher than average in Avon, Holbrook, Medfield, Medway, Sharon and Wrentham. Culex pipiens/restuans populations have remained high in Quincy. Psorophoraferox populations remain higher than average in Canton.

Gravid Traps:
It appears as though Ochlerotatus japonicus gravid mosquitoes are on par or more numerous than Culex pipens/restuans mosquitoes. Uranotaeniasapphirina have become more common as the weather turns cooler.

3. Comparison to previous season

Compared to the previous seasons, host-seeking mosquito collections in CDC traps this week were once again mixed. Culiseta melanura populations remain higher than average in Avon, Holbrook, Medfield, Medway, Sharon and Wrentham. Most towns are reporting average levels of mosquito activity. The continuing cool weather has decreased our collection of gravid mosquitoes and it appears as though the Ochlerotatus japonicus collected are on par with those of Culex pipiens/restuans. Gravid collections across the county are lower than average to average in size.

4. Weather Summary

This week started with patchy frost on the morning of Sept. 20th, as Norwood airport reported a low temperature of 31 degrees. This was followed by dry and warmer than normal temperatures. Another strong cold front on Thursday paved the way for another frost in portions of the region by Saturday morning; however it was patchy at best. Norwood airport reported a low of 32 that morning, while frost was also reported in Bellingham. According to data from stations at Weather Underground (wunderground.com), localities that may have experienced frost (temperatures at 35 degrees or below) included Medfield (33 deg), and Medway (34.8 deg). A low pressure system brought some periodic rain on Sunday the 27th however it was fairly light with a ¼ to ½ inch across the county.

Total weekly rainfall: 0.28 inches (-0.66 in.)
Total Monthly rainfall: 2.00 inches (-1.12 in.)
Total Yearly rainfall: 32.21 inches (+1.39 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 localized low level activity for one mammal biting mosquito species, Aedes vexans. Some CDC light traps are also showing fairly high levels of Culiseta melanura. NCMCP plans to continue adult mosquito surveillance through the first full week of October after which all trapping activities will be terminated. 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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