Week 29 – July 16 – 17

2008 Mosquito Report: Week 29

Report based on data collected from traps deployed on Wednesday, July 16, 2008 and retrieved on Thursday, July 17, 2008. Report prepared by John Smith, Chan Suom, M.S., and Nate Boonisar.

1. Current mosquito activity/trend

CDC Light Traps:
Except for the towns of Avon, Canton, Millis, and Wrentham (which have seen an increase in Culiseta melanura), activity level for CDC traps this week remains low once again compared to last year. The most predominant CDC trapped mosquitoes were once again Coquillettidia perturbans, the numbers of which have climbed to more average numbers this week in several traps. In addition, the towns of Medway and Weymouth (north) have also experienced an increase in Culiseta melanura activity. Aedes vexans has made a significant appearance in Canton with smaller collections in other traps across the county. Although not reflected in trap data, service requests and site visits in the City of Quincy indicate an emergence of salt marsh mosquitoes (Ochlerotatus sollicitans) in coastal areas. There is also evidence of greenhead fly and biting midge activity.

Gravid Traps:
Mosquito activity in gravid traps has remained relatively steady compared to last year’s figures with notable increases in activity in the towns of Avon,Bellingham, Holbrook, Medway, Millis, Milton, Norwood, Quincy, Randolph, Sharon, and Weymouth. The general trends seem to be continuing with the highest numbers of Culex pipiens/restuans collected in the traps located in the eastern third of the county with only a few notable exceptions (Medway & Bellingham). Ocherlotatus japonicus collections remain low.

2. Current Predominant Species

The most predominant CDC trapped mosquitoes were Coquillettidia perturbans and Culiseta melanura. Culex pipiens/restuans is the most abundant species collected in gravid traps.

3. Comparison to previous season

CDC activity is down this week compared to last year’s data for mammal biting mosquitoes. The weather has been relatively dry and has impeded reflood mosquito emergence by limiting/eliminating habitat. There were a few thunderstorm/rain events that have allowed for this season’s first significant presence of Aedes vexans in Canton. Coquillettidia perturbans numbers are now approaching “normal” levels in a few traps following a typical bell shape curve. Several traps are still showing low numbers of this species which is unusual for this time of year. Gravid trap activity is similar to last year’s figures with increased activity in the towns noted above.

4. Weather Summary

There were two episodes of rainfall across Norfolk County this week. The first was a heavy shower on Monday that moved across the entire county dumping between 0.1 to 0.5 inches county wide in a short period of time. The second rainfall occurred on Friday when a line of thunderstorms developed across eastern areas, giving up to 0.30 inches across far eastern sections. County wide, total weekly rainfall was under 0.75 inches. Thus the longer term trend of dry weather continued. Temperatures were near normal to begin the week, to above normal by the end of the week.

Total weekly rainfall: 0.39 inches (-0.29 in.)
Total Monthly rainfall: 2.28 inches (+0.41 in)
Total Yearly rainfall: 24.14 inches (+0.99 in.)

5. Number of requests for service

Year to date NCMCP has received 2,351 calls for service as of 7/19/08. This represents a total of 260 calls for the week. This shows a decrease in calls from last week. Last year at this time the calls for service (year to date) were 3,910. Calls for service this year continue to run almost 1,500 less than at this same time last year.

6. MCP/Commission response

In general our response has been to continue ground ULV applications targeting areas of high public demand. NCMCP is making good progress toward treating rain basins in highly urban areas where Culex pipiens/restuans activity is highest.


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