For Week Ending August 1, 2008

 

MOSQUITO COUNTS - Mosquito activity is (hopefully) at its peak this week.  The weather, especially nighttime temperatures, should begin to cool down in August, slowing down the breeding cycle.   We've been lucky this season to have a cool spring and a dry summer, which have helped us keep on top of the mosquitoes.  However, it looks like last week's rain has prompted more mosquito breeding in the towns, where we are trapping more Culex than ever so far this season.  With the monsoon season upon us, it's more important than ever to check your property for any potential containers such as tarps, wading pools, buckets, cans, tires, flower pots, clogged gutters, plastic toys, etc.  Other hard-to-find water sources include leaky or broken sprinkler and irrigation systems, seepage from unlined ditches or underground pipes, leaky roofs on sheds and outbuildings, and seepage or leaks under houses or trailers.  Our larvicide teams are out in the fields all day treating the bigger sites, so people will need to take responsibility for their own smaller properties.  If you need assistance or if your standing water cannot be easily eliminated, call us and we will send someone out to help assess, clean up, and/or treat your site.

 

BMW RALLY - On a positive note, all reports from the campers at the BMW Rally in Paonia were complimentary.  A few mosquitoes were seen and were thick by the river, but at the camp sites and in the Town Park, no one reported being bothered by mosquitoes.  Many of the participants came from other parts of the country where they have "real mosquitoes," and they were pleased to be able to enjoy being out of doors in the summertime here.

 

WEST NILE VIRUS - According to the Colorado Health Department, there have now been 13 confirmed cases of West Nile Fever and 1 confirmed case of West Nile Encephalitis in Colorado, all along the Front Range.  There has not yet been any WNV found in mosquitoes collected on the Western Slope, though it takes at least 2 weeks for those results to come in.   (See the CDPHE link to the left to get the latest figures direct from the source).  August and September are traditionally the months when most of the human cases are identified, mostly because it takes so long from the time of exposure (the mosquito bite) to the time it is confirmed with the CDC.  July is usually the month of greatest Culex activity, but the mosquitoes may be more likely to get and spread WNV later in the season when the virus has had a chance to spread through the bird and mosquito population.  The mosquitoes, who usually prefer birds for their blood meal, may also be more likely to go after humans or other animals later in the season when the availability of nestlings goes down.  Be sure to take precautions, avoiding going outside after dark and wearing long sleeves and long pants as well as mosquito repellent if you do.

 

FOGGING - Fogging operations continue on a similar schedule to last year as most of our trap counts exceed our (admittedly conservative) thresholds.  We continue to get better trapping data as our pool of available traps and volunteers goes up.  THANK YOU, VOLUNTEERS!  Trapping is labor-intensive and takes some training as well as meticulous attention to detail. With this data, we are able to narrow the focus of our larviciding and fogging efforts.  We have discovered that high concentrations of mosquitoes are fairly localized, which means the trapping data give us clues as to where to look for breeding sites and let us know which areas don't really need to be fogged.  We have learned that we can indeed use more targeted fogging, as the trap results tell us that high mosquito counts go down after a fogging event, while in nearby areas with low counts which are not fogged, the counts remain about the same the following week.  There is no evidence that mosquitoes "move" en masse to escape the fog, though certainly the ones flying at the edges of the pesticide cloud may avoid it until it settles.  In fact, the fog truck drivers report the mosquitoes seem to be attracted to the heat and moisture produced by the ULV fogger.  If there is a large outbreak, say around many acres of fields, the fogging truck will cut a swath through it along the route it takes, but if there are a lot of mosquitoes still out in an unfogged area of the field, they will fill in the fogged area after a few hours. That doesn't mean the Biomist is ineffective, only that it can't reach into areas too far from the road.  All the more reason to larvicide the fields (which can kill about 80-95% of the mosquitoes) or, better yet, make sure they don't have standing water on them for more than a few days (which will eliminate 100% of them).