Week 26 – June 24 – 25

2009 Mosquito Report: Week 26

Report based on data collected from traps deployed on Wednesday, June 24, 2009 and retrieved on Thursday, June 25, 2009. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
The towns of Dedham, Foxboro, Franklin, Medway, and Norfolk experienced moderately higher host-seeking mosquito activity while CDC trap activity across the county has been low or similar to last year’s data.  CDC mosquito collections in general have been light due to poor weather conditions for trapping. We do not believe the collections are representative of the populations at this time and expect to see higher numbers once the weather improves.

Gravid Traps:
Gravid traps in most towns collected low numbers although higher than average collections were noted for the following towns: Canton, Franklin, andWeymouth. Gravid trap collections have been limited due to poor weather conditions.  Some trap sites are showing higher numbers of Culexpipiens/restuans which would be expected due to their more urban locations.  We are collecting some Oc. japonicus but in very low numbers.

2. Current Predominant Species

CDC Light Traps:
The most predominant mosquito species in CDC traps is Coquillittedia perturbans the numbers of which are beginning to rise. Numbers of this species were above average in the Franklin and Medway traps. We still feel that these collections are not representative of actual populations due to poor trapping conditions. Ochlerotatus canadensis collections have been average to below average across the county.  Ae. vexans have been low to zero in most traps.  Recent rain events may (?) increase numbers of summer refloods especially in the west – central portion of the county due to isolated heavy rainfall. Due to excessively high monthly tides (13 feet +) we are anticipating an emergence of salt marsh mosquito species towards the later half of the week ending July 3rd . This will affect coastal areas of Quincy, Weymouth and Milton. Culiseta melanura numbers remain low. Again it is hard to determine their actually numbers due to poor trapping conditions.

Gravid Traps:
Gravid traps are dominated by Cx. pipiens/restuans at low levels.

3. Comparison to previous season

Comparisons with last years trapping data would not be useful due to poor weather conditions for trapping so far in 2009.

4. Weather Summary

A nearly stationary area of low pressure provided cloudy, drizzly and cool temperatures through much of the week, with some periods of heavier rain earlier in the week.  This rain served mainly to provide relief from prior dry conditions and it did not have a significant effect on our rivers.  On Saturday, a seabreeze boundary ignited thunderstorms over Foxborough and Sharon that sat nearly stationary for three hours.  A National Weather Service spotter in Foxborough reported over 2 inches of rain in under an hour with numerous streets flooded, while another spotter in adjacent Mansfield received nearly 3.5 inches of rain. Storm total precipitation analysis indicated possibly up to 5 inches of rain in portions of these towns, however, some of that may have been hail contamination.  Either way, this rain may have had a significant effect on our wetlands. Some of it fell on the headwaters of the Neponset Rivercreating significant rises downstream.  Attached is a map of the weekly rainfall across the county.

Total weekly rainfall: 2.28 inches (+1.55 in.)
Total Monthly rainfall: 4.32 inches (+1.42 in.)
Total Yearly rainfall: 19.54 inches (-1.42 in.)

5. Number of requests for service

NCMCP received 1,098 calls for service as of 6/26/09. NCMCP received 268 calls for service this week.

6. MCP/Commission response

NCMCP has been conducting sporadic “area wide” ground ULV applications when and where possible although poor weather conditions have delayed applications in many high call areas. It will take some time for NCMCP to service these request IF weather conditions stabilize. Coordination between NCMCP and the 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 larvicide control activities as required.


144 Production Rd, Suite C

Walpole, MA 02081

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