Week 32 – Aug 8-13

2011 MOSQUITO REPORT: WEEK 32

Report based on data collected from traps deployed the week of August 8, 2011 through August 13, 2011. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. CURRENT MOSQUITO ACTIVITY/TREND

CDC Light Traps:
Host-seeking activity throughout Norfolk County continues the trend of low collections for this week. Almost all towns returned trap collections with lower than average numbers of mosquitoes. Only parts of Walpole indicated higher than average mosquito activity.

Gravid Traps:
Last week’s mostly higher than average gravid mosquito collection does not continue into this week. Most towns had lower than average collections of mosquitoes. Only Canton, Dover, Norwood, and Weymouth collected higher than average mosquitoes in their respective traps.

2. CURRENT PREDOMINANT SPECIES

CDC Light Traps:
Culiseta melanura continues to be very populous in Holbrook, parts of Sharon, and Walpole. Coquillettidia perturbans numbers continue to decline. Host-seeking activity was generally low throughout the county, so there isn’t much of a reference to make. On the other hand, we expect a higher number of Aedes vexans in next week’s trap collections due to the recent streak of rain events.

Gravid Traps:
Gravid Culex pipiens/restuans mosquito populations are mostly low this week. Oc. japonicus numbers are about average.

3. COMPARISON TO PREVIOUS SEASON

The continued scattered thunderstorms and low overnight temperatures (60’s) during our trapping period seems to have hindered both host-seeking and gravid mosquito activity this week. Last week’s similar weather pattern returned higher gravid mosquito activity. An interesting observation is the increase of Cs. melanura populations that has coincided with the previous weeks’ trend of steady rain events, which may likely be creating plentiful Cs.melanura habitat within the wetlands crypts.

4. WEATHER SUMMARY

The weather pattern turned fairly active this week with significant rains across most of the area. Sunday and Tuesday featured widespread soaking rains, whereas Monday and Wednesday’s rains were primarily from thunderstorms. Weekly rainfall increased fairly uniformly from east to west across the county; from as low as 1.5 inches in extreme eastern areas, to nearly five inches in the northwest. The whole county has averaged near normal to above normal precipitation over the past 30, 60, and 90 days. The rainfall this week did not cause any widespread flooding on our rivers, however, scattered pockets of water may have accumulated on some of the flood plains. Also, the Neponset, and to a greater extent, the Charles River are running above normal for this time of year, which has primed them in the event of further significant rainfall.

Total weekly rainfall: 3.86 inches (+3.11 in.)
Total Monthly rainfall: 3.90 inches (+2.53 in.)
Total Yearly rainfall: 28.36 inches (+2.66 in.)

5. NUMBER OF REQUESTS FOR SERVICE

NCMCP received 5,998 calls year to date for service as of 8/12/11. NCMCP received 354 calls for service this week.

6. MCP/COMMISSION RESPONSE

NCMCP continues “area wide” ground ULV applications in high request areas and in areas where collection data indicate a need. Rain basin treatments continue with a concentration in urban areas where West Nile virus (WNV) has been collected historically. NCMCP is also prioritizing basin treatments adjacent to areas in Boston where West Nile virus has been identified. NCMCP continues some ground larviciding in coastal areas in response to flooding due to frequent rain events. Due to the positive WNV isolates in mosquitoes collected in Dedham, Dover, Needham, Norwood and Quincy, NCMCP has conducted localized (focused) applications of both ULV and rain basin treatments. Boards of Health in all communities have stepped up public outreach using all available local media outlets.

Contact

144 Production Rd, Suite C

Walpole, MA 02081

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