Week 26 – June 24-30


Report based on data collected from traps deployed the week of June 24, 2012 through June 30, 2012. Report prepared by Chan Suom, M.S., Dave Lawson, and Nate Boonisar.


CDC Light Traps:
Host seeking mosquito populations vary widely this week. The towns of Canton, Franklin, Holbrook, Needham, and Wrentham reported lower than average collections, whereas most of the county had between average and higher than average trap collections.

Gravid Traps:
Gravid trap collections are higher than average in most parts of Norfolk County this week. The towns of Avon, Holbrook, and Westwood collected lower than average numbers of ovipositing mosquitoes.


CDC Light Traps:
The most predominant CDC trapped mosquitoes in Norfolk County this week were Coquillettidia perturbans; this species usually reaches its peak around the 4th of July but with such large collections before then we could expect a prolonged population well after the 4th of July. Aedes vexans populations are higher than average in Bellingham and Dedham but its presence in the county has dropped since these species depend on flooding for emergence. Ochlerotatus canadensisis out in full force in Medfield, Millis, and especially in Sharon. Culex pipiens/restuans populations are higher than average in Bellingham, Dedham, Milton, and Quincy. Ochlerotatus cantator, a salt marsh/coastal mosquito, is starting to make a noticeable appearance in Quincy and will inevitably be bothersome to beachgoers as they are mammal biters.

Gravid Traps:
Culex pipiens/restuans are the most predominant species in gravid traps throughout Norfolk County.


The varied collections from lower to higher than average collections this week was due to localized thunderstorms during our trapping interval. Some areas were cooler than others and a combination of wind may have played a role in the decline of mosquito numbers in certain towns that usually collect more. The heat wave of 90+ degrees (F) we’ve had probably has much to do with the decline of mosquito populations in other towns.  Culiseta melanura and Culex pipiens/restuans inhabit permanent bodies of water, so their numbers are not as affected (actually higher than average this week) as species that depend on vernal pools. We suspect that the wetlands in our trap-site in Holbrook may have dried out, resulting in lower than expected Culiseta melanura. A visit to this wetland is planned for next week to investigate the matter, although a lower population of the EEE-virus vectoring Culiseta melanura is more than welcomed!


This weak featured near to slightly above normal temperatures with above normal precipitation. Widespread showers and thunderstorms occurred on Monday morning bringing 1 – 1.5 inches throughout most of the district, with slightly lesser amounts in the far west. Widely scattered thunderstorms occurred through mid-week but with amounts under ¼ inch where they did occur. A more widespread area of brief showers passed by on Friday morning, but with amounts generally between 0.1 and 0.2 inches district-wide.

Total weekly rainfall: 1.42 inches (+0.68 in.)
Total Monthly rainfall: 3.98 inches (+0.76 in.)
Total Yearly rainfall: 14.96 inches (-6.32 in.)


NCMCD has received 2,937 calls year to date for services as of 6/30/12. The NCMCD received 504 calls for service this week.


The NCMCD continues to respond to ULV requests by residents. With some overtime work by the field crew and a slight drop off in the rate of requests, we have been able to ‘catch up’ with treatments in almost all the towns. Basin treatments continue in all municipalities. Very few larvicide requests are being initiated at this time. Some of the locations are treated for mosquito larvae but most are either dry or have no larvae.


144 Production Rd, Suite C

Walpole, MA 02081

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