Week 35 – Aug 26 – 27

2009 Mosquito Report: Week 35

Report based on data collected from traps deployed on Wednesday, August 26, 2009 and retrieved on Thursday, August 27, 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 was mixed once again throughout Norfolk County. Higher than average mosquito activity was recorded in the towns of Avon, Canton, Dedham, Foxboro, parts of Franklin, Holbrook, Medway, parts of Millis, Milton, Norfolk, Plainville, parts of Sharon, and parts of Walpole. Lower than average mosquito activity was experienced in parts of Franklin, parts of Millis, Quincy, parts of Sharon, and parts of Walpole. The towns of Bellingham, Braintree, Medfield, Needham, and Weymouth recorded average levels of host-seeking mosquito activity.

Gravid Traps:
Gravid traps have once again dropped below average levels of activity across Norfolk County. The only towns reporting average numbers of gravid mosquitoes were Braintree, parts of Foxboro, Norfolk, parts of Sharon, and Westwood.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC trapped mosquitoes in Norfolk County this week were Aedes vexans (Avon, Canton, Dedham, Millis, Milton, and Norfolk) and Anopheles punctipennis (Avon, Dedham, Franklin, Holbrook, Plainville, and Walpole). Culiseta melanura has remained highly active in Avon. Ochlerotatus canadensis populations are high in Foxboro and Sharon, but have dropped in Millis. Culex pipiens/restuans populations are higher than average in the towns of Foxboro, Medway, and Wrentham. Psorophora ferox populations continue to be higher than average in Canton.

The Charles and Neponset River flood plains have dried down to near normal conditions. Even with the drier weather, site visits continue to show high levels of human biting mosquito activity. Field Crews have been dispatched to check for larval development on the salt marshes following the monthly high tide on August 20th and the storm surge from Hurricane Bill.

Gravid Traps:
Although gravid traps remain predominated by Culex pipiens/restuans, their abundance was lower than average across Norfolk County. Anopheles punctipennis populations were higher than average once again in parts of Dedham. Ochlerotatus japonicus numbers are average throughout the county.

3. Comparison to previous season

Host-seeking mosquito activity this week was mixed, with higher than average numbers attributed to sporadic, localized Aedes vexans and Anophelespunctipennis populations. Culex pipiens/restuans populations have dipped throughout the county, but remain higher than average in scattered regions of the county as noted in the above-referenced towns. Consistent with previous weeks’ activity, Psorophora ferox numbers continue to be high in Canton. Gravid trap activity has dropped once again in most parts of Norfolk County. Anopheles punctipennis populations are high in parts of Dedham.

4. Weather Summary

The heat and humidity continued during the early part of the week, but a strong cold front brought much cooler and drier weather for the end of the week. A hybrid tropical/coastal low pressure system (Tropical storm Danny) brought heavy rain to the area on Saturday. Rainfall amounts for this system were generally from 1.5 to just over 2 inches across the county with the heaviest rain in the far northeastern sections. This brought monthly rainfall to normal levels for most of the county with yearly rainfall remaining above normal. Due to the prior dry conditions for the month, this rainfall was not enough to create any significant flooding on our area rivers.

Total weekly rainfall: 1.62 inches (+0.95 in.)
Total Monthly rainfall: 3.40 inches (+0.26 in.)
Total Yearly rainfall: 30.21 inches (+2.73 in.)

5. Number of requests for service

NCMCP received 5,399 calls for service as of 8/28/09. NCMCP received 371 calls for service this week.

6. MCP/Commission response

NCMCP continues to conduct “area wide” ground ULV applications in specific areas of the county due to high numbers of calls. Calls for service declined slightly from last week to this week but are still running high. The main areas of concern are in towns adjacent to the Charles and NeponsetRiver flood plains. A spike in Oc. sollicitans in the North Weymouth area has caused a fairly dramatic increase in complains. The issue is aCommonwealth of Mass. drain easement – broken drainage node which is dispersing salt water onto a small marsh. NCMCP has approached Weymouth Engineers for the purpose of investigating options for a long term source reduction solution to this problem. NCMCP is wrapping up treatments to rain basins in high density basin areas such as centers of towns. As a result of the positive WNv mosquito pool in west central Quincy, NCMCP conducted a ULV application in the area. All rain basins in the area have been treated. 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.


144 Production Rd, Suite C

Walpole, MA 02081

Office: (781) 762-3681
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