Week 33 – Aug 12 – 13

2009 Mosquito Report: Week 33

Report based on data collected from traps deployed on Wednesday, August 12, 2009 and retrieved on Thursday, August 13, 2009. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Continuing with last week’s trend, most towns in Norfolk County reported higher than average host-seeking mosquito activity. Canton reported lower than average Ae. vexans, but higher than average Co. perturbans and Ae. cinereus activity. Parts of Walpole experienced a lower than average catch reflecting a decreased population of Co. perturbans. Bellingham, Needham, Plainville, and parts of Walpole and Weymouth reported average numbers.

Gravid Traps:
Most towns in Norfolk County experienced yet another lower than average gravid mosquito collection. Canton and Medway saw increased mosquito activity due to increased Culex pipiens/restuans populations. Milton experienced higher than average gravid mosquito activity due to an unusually highOc. japonicus presence.

2. Current Predominant Species

CDC Light Traps:
The most predominant CDC trapped mosquitoes in Norfolk County this week were once again Aedes vexans and Coquillettidia perturbans. Anophelespunctipennis populations were higher than average in Dedham. Culex pipens/restuans populations were high and spread throughout the county in light traps. Oc. canadensis populations continue to be high in the towns of Foxboro and Sharon, and are now increasing in numbers in the Millis light trap. Avon, Foxboro, and Holbrook experienced higher than average Cs. melanura activity. The town of Quincy light trap collected an unusually high number of Oc. excrucians this week. Ae. cinereus populations are higher than average in Canton. The Charles and Neponset River flood plains have dried down to near normal conditions. The USGS stream flow monitoring station on the NeponsetRiver in the Norwood area is indicating a flow at the 75th to 89th percentile which means this river system is still prone to flooding. The good news, as detailed in the weather report below, shows no significant rainfall recorded since July. With the recent formation of several tropical storms/depressions in the Atlantic all eyes are on the tropics!!! Even with the dry weather, site visits continue to show high levels of human biting mosquito activity with landing rates remaining unchanged from Epi Week 31.

Gravid Traps:
Although gravid trap collections remain predominately Culex pipiens/restuans, there appeared to be a slightly higher gravid population of Oc. japonicusmosquitoes, especially in the town of Milton.

3. Comparison to previous season

Host-seeking mosquito activity this week was mostly higher than average due to the continued, staggered emergence of Co. perturbans, and the lingering populations of Ae. vexans, and Oc. canadensis populations. This week saw an atypically high population of Ae. cinereus, An. punctipennis, and Oc.excrucians in some towns. Except for the towns of Canton, Medway, and Milton, gravid trap activity for Norfolk County was lower than average continuing with the past few weeks’ low collection trend.

4. Weather Summary

This week was cooler yet still humid. A relatively dry pattern continued with the only significant rain falling on the 11th, when thunderstorms produced ¼ to ½ inch of rain across most of the county with lesser amounts in the southwest. On the 13th, an offshore storm produced a general light rainfall with amounts on either side of a tenth of an inch. Otherwise, there was a return to warm and humid weather at the end of the week. With the dry weather pattern, rainfall for the month is running well below normal across the entire county.

Total weekly rainfall: 0.44 inches (-0.32 in.)
Total Monthly rainfall: 0.44 inches (-1.15 in.)
Total Yearly rainfall: 27.25 inches (+1.33 in.)

5. Number of requests for service

NCMCP received 4,576 calls for service as of 8/14/09. NCMCP received 468 calls for service this week.

6. MCP/Commission response

NCMCP continues to conduct “area wide” ground ULV applications in many areas of the county due to high numbers of calls as a result of these large populations of human biting mosquitoes. Due to an increase in demand these ULV activities have been expanded across the county again this week. NCMCP continues treatments to rain basins in high density basin areas such as centers of towns. 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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Walpole, MA 02081

Office: (781) 762-3681
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