Week 27 – June 30-July 1

2009 Mosquito Report: Week 27

Report based on data collected from traps deployed on Tuesday, June 30, 2009 and retrieved on Wednesday, July 1, 2009. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Compared with last year’s trap data, most towns in Norfolk County experienced an average to lower than average activity of host-seeking mosquitoes. The towns of Avon, Bellingham, Foxboro, Franklin, Medway, Norfolk, Sharon, and Wrentham experienced higher than average host-seeking mosquito activity primarily due to a surge in Coquillettida perturbans populations.

Gravid Traps:
Similar to the CDC trap data, this week’s gravid mosquito collections were average to below average compared with last year’s numbers. Only Dedham,Franklin, Medway, and Plainville experienced higher than average gravid mosquito activity.

2. Current Predominant Species

CDC Light Traps:
Once again the most predominant CDC trapped mosquitoes this week were Coquillettidia perturbans. We are beginning to collect small numbers ofAedes vexans which indicates an emergence has begun. We anticipate that these numbers will increase significantly within a week or so. Recent rain events should increase numbers of summer refloods especially in the west – central portion of the county due to isolated heavy rainfall. Field personnel are picking up 1st to 4th instars and pupae in dip surveys. Due to recent excessively high monthly tides (13 feet +) we are anticipating an emergence of salt marsh mosquito species shortly. This will affect coastal areas of Quincy, Weymouth and Milton. Culiseta melanura numbers remain low in most locations collected with the exception of Holbrook where the collection was above the average. Again it is hard to determine their actually numbers due to poor trapping conditions.

Gravid Traps:
Culex pipiens/restuans are the most abundant species in gravid traps. Ochlerotatus japonicus populations are slowly increasing and are on par with Culexspecies in some towns.

3. Comparison to previous season

For the most part, CDC activity is down this week compared to last year’s data for host-seeking mosquitoes, although there is increased activity in the above-mentioned towns. Ovipositing mosquito activity is low this week when compared to last year’s figures. This week’s trap collection data is not representative of what is usual for this time of year due to the ongoing inclement weather pattern.

4. Weather Summary

A continuation of the same weather pattern led to cool temperatures and periods of heavy rain and thunderstorms across the county this week. Rainfall over the past seven days has ranged from around 1.5 inches in the east to 3 inches in the west (seven day totals of 5-6 inches remain across Foxboro and Sharon). Rainfall amounts have been above normal over the past 60-days, while over the past 90 days, rainfall has averaged slightly below to slightly above normal across the county (90-150% of normal). Year to date rainfall remains slightly below normal across much of the county with a pocket of near normal rainfall across south central areas. Much of the recent weeks’ rainfall has served to significantly lessen yearly deficits. River levels are above normal for this time of year and are at levels that allow for some local spillover onto the flood plains.

Total weekly rainfall: 1.85 inches (+1.35 in.)
Total Monthly rainfall: June: 4.56 inches (+1.34 in.), July: 1.61 inches (+1.41 in.)
Total Yearly rainfall: 21.39 inches (-0.09 in.)

5. Number of requests for service

NCMCP received 1,381 calls for service as of 7/03/09. NCMCP received 287 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. NCMCP began treating rain basins the first week of June although these activities have been interrupted from time to time due to redeployment of field staff to other groundlarvicide activities associated with treatments targeting tidal and heavy rain event flooding. 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 has also been coordinating with local officials for adult control treatments in advance of town sponsored events such as band concerts and fireworks displays. 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