Week 35 – Aug 30-Sept 3

2010 Mosquito Report: Week 35

Report based on data collected from traps deployed the week of August 30, 2010 through September 3, 2010. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
CDC light trap collections indicate host-seeking mosquito activity from average to below average across most of Norfolk County. Only Franklin and Norfolkreturned higher than average collections.

Gravid Traps:
Gravid mosquito activity is average for most of Norfolk County. Dedham, Medway, Norwood, Stoughton, and Westwood report higher than average activity whereas Avon, Canton, Holbrook, Milton, Randolph, Sharon, and Wrentham indicate declining populations.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC-trapped mosquitoes in Norfolk County this week are Anopheles walkeri and Uranotaenia sapphirina. Coquillettidia perturbanspopulations are sparse and quickly declining. A recent emergence of Ochlerotatus sollicitans (salt marsh mosquito) in the northeastern part of the county has also gone into decline.

Gravid Traps:
Culex pipiens/restuans populations average throughout most of Norfolk County. Ochlerotatus japonicus numbers are average also.

3. Comparison to previous season

Host-seeking mosquito activity continues to be low into this week. The primary factor affecting this is cooler overnight temperatures during our trapping schedule. Container breeders and permanent water body species are the most common collections in our traps. WNv has been been isolated within NorfolkCounty for the second week, with Dedham and Norwood gravid collections going positive. Although host-seeking populations are low, EEE and WNv continue to be isolated in or around the borders of Norfolk County. Gravid mosquito activity has normalized throughout most of the county, but the threat of viremic and infective mosquitoes is still high in Dedham and Norwood. Caution and personal protection should be practiced while engaging in outdoor activities withinDedham, Norwood, and the immediate areas.

4. Weather Summary

This week was hot and increasing humid with no rainfall. Hurricane Earl passed well southeast of the area Friday night into Saturday morning bringing some rainfall to the county but the heaviest rain remained to the southeast. Amounts generally ranged from ¼ to ¾ of an inch county-wide, highest amounts in the west. The U.S. Dept. of Agriculture has now removed most of the county (except for the far west) from the “Abnormally dry” category on the Drought Monitor, this due to heavy rains in late August.

Total weekly rainfall: 0.55 inches (-0.24 in.)
Total Monthly rainfall: Aug: 4.67 inches (+1.30 in.), Sept: 0.55 inches (+0.10 in.)
Total Yearly rainfall: 36.01 inches (+7.85 in.)

5. Number of requests for service

NCMCP received 6,955 calls year to date for service as of 9/3/10. NCMCP received 273 calls for service this week.

6. MCP/Commission response

NCMCP ground ULV applications continue at a low level with the exception of Norwood and Dedham where ULV applications have been expended in response to WNV positive mosquito pools collected in Epi Weeks 34 and 35. Overall complaints from residents (year to date) continue at levels higher than in the past three years although this weeks numbers (similar to Epi Week 34) were down. NCMCP has wrapped up treatments of rain basins. Concern is mounting along the eastern edge of the county due to an increase in WNV isolates in the towns of Dedham and Norwood as well as bordering communities of Newton, Brookline and Boston. As reported above, one of the two gravid trap sites in the Town of Dedham collected West Nile Virus positive mosquitoes as well as the Norwood gravid trap site. NCMCP is coordinating with the Dedham Health Department adult control applications. Public outreach continues in the areas of positive collections. NCMCP deployed additional gravid traps in the Town of Dedham and Norwood.


144 Production Rd, Suite C

Walpole, MA 02081

Office: (781) 762-3681
Fax: (781) 769-6436