Week 30 – July 25-29

2011 MOSQUITO REPORT: WEEK 30

Report based on data collected from traps deployed the week of July 25, 2011 through July 29, 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 declined dramatically this week. Almost all towns returned trap collections with lower than average numbers of mosquitoes. Only Quincy and parts of Weymouth experienced higher than average mosquito activity.

Gravid Traps:
As with CDC light trap data, most towns reported lower than average gravid mosquito activity. The towns of Dedham, Dover, Medfield, Norwood, parts of Quincy, Westwood, and Weymouth collected higher than average numbers of gravid mosquitoes, whereas Canton, parts of Foxboro, Needham, parts of Quincy, and Sharon returned average numbers of gravid mosquitoes from their respective traps.

2. CURRENT PREDOMINANT SPECIES

CDC Light Traps:
Culiseta melanura was very populous in Holbrook, with higher than average numbers for this week. Aedes vexans populations remain higher than average in parts of Weymouth. Oc. sollicitans are becoming more prominent in Quincy. Meanwhile, Oc. canadensis and Oc. excrucians are higher than average for this time of year in Canton.

Gravid Traps:
Gravid Culex pipiens/restuans mosquito populations are mostly lower than average for the week. Oc. japonicus numbers are about average.

3. COMPARISON TO PREVIOUS SEASON

The week’s scattered thunderstorms and low overnight temperatures (60’s) during our trapping period have much to do with the overall lower than average mosquito collections throughout the county. New Co. perturbans populations are still appearing throughout the county, but in very small numbers compared to the earlier part of the season.

4. WEATHER SUMMARY

Temperatures this week were generally near normal with below normal rainfall county-wide. The main precipitation came from weakening showers and thunderstorms both Monday and Tuesday and again Friday/Saturday morning, generally bringing weekly totals of ¼ to ½ inch county-wide, with some amounts over ½ inch in the north. Total July rainfall around the county was highly variable ranging from 25-75% of normal, with the least amounts in the north. There were localized areas of above normal rainfall in southern areas. Below is a list of July rainfall from around the county (taken from Weather Underground personal weather station data).

Total weekly rainfall: 0.40 inches (-0.30 in.)
Total Monthly rainfall: 1.83 inches (-1.13 in.)
Total Yearly rainfall: 24.46 inches (+0.23 in.)

5. NUMBER OF REQUESTS FOR SERVICE

NCMCP received 5,233 calls year to date for service as of 7/29/11. NCMCP received 491 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. Rain basin treatments in the eastern areas where gravid traps are showing high levels of Culex have been prioritized. NCMCP is also prioritizing basin treatments adjacent to areas in Boston whereWest Nile virus has been identified. ULV applications have been conducted in these adjacent areas due to the high numbers of Culex collected in gravid traps. NCMCP continues some ground larviciding in coastal areas. Due to the positive WNV isolates in mosquitoes collected in Dedham and Quincy, NCMCP has conducted localized (focused) applications of both ULV and rain basin treatments. Boards of Health in both 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