Asian tiger mosquito a focus of last week's training

Keith Haas demonstrates use of a handheld ULV applicator
for treating adult mosquitoes hiding in dense vegetation.

For which important urban insect pest did 70% of pest control companies get more calls last year? For which pest are 88% of pest management professionals (PMPs) confident that control options are better than they were five years ago?  For what pest do nearly 2/3 of companies have callback rates of 4% or less?

According to a 2017 report by MGK^® Co., the repeated answer is "mosquitoes". It appears that pest control customers increasingly want to fight pesky mosquitoes in their backyards, and are willing to pay for it. 

Ultimately, this increased interest in mosquitoes is what brought 15 interested PMPs to the "Practical Mosquito Control" course last week at IPM Experience House. And, as students learned, the driving force for this demand may just be the tiny Asian tiger mosquito (ATM), Aedes albopictus, and its slightly less common cousin the yellow fever mosquito, Aedes aegypti.

A fast and opportunistic biter, tiger mosquitoes are relatively new pests, having arrived from Japan only about 30 years ago. When people complain that, "the mosquitoes are terrible this time of year", chances are they're talking about the day-flying ATM. But ironically, despite it's irritating bite, ATM is not currently a public health threat in most areas.

"The one good thing about ATM", said Scott Sawlis, county entomologist for Dallas County Health and Human Services, "is that it reminds people that they need to wear repellent, and thereby protect themselves from the more dangerous disease-carrying species."  In the Dallas area that would be Culex quinquefasciatus, the stealthier, nighttime-flying, southern house mosquito.  Even though folks don't tend to notice the house mosquito as much, it's the one to carry West Nile virus, our most serious mosquito-borne disease. 

Sawlis and fellow instructors (myself and Dr. Sonja Swiger with Texas A&M AgriLife, and Keith Haas, with Central Life Sciences), spent the day explaining to class attendees about the need for mosquito control, and some of the differences between the target species.  At the end of the day we got to practice what we learned in class by conducting an outdoor inspection and spending some workout time on microscopes looking at these tiniest of pests at a bug eye level. 

During our inspection we discovered mosquitoes breeding (naturally) just a few feet from where class took place.  Afterwards, students got to see fresh-caught mosquito eggs and watch mosquito larvae wriggle through murky breeding media.  Haas demonstrated the ability of a ULV generator to go through and around landscape vegetation, and Sawlis demonstrated proper use of a dipper when trying to determine whether mosquitoes might be breeding in a water source.

Although ATM may be one of the best things to happen to the pest control business in the past few years, it does have a darker side. The ATM is very difficult to control from city spray trucks and even from the air.  And it remains ready to transmit the viruses for Zika and dengue fever, should these diseases arrive in our area like Zika did last summer in Miami, FL and Brownsville, TX.  

One of the most effective tools, our class learned, for fighting tiger mosquitoes is the PMP. While county and city mosquito control staff must patrol streets with sprayers that treat city-blocks at a time (a technique that works well for the house mosquito), only the PMP walks backyards, identifies and treats ground-level breeding sites, and precisely targets sprays to ATM resting sites. This puts the pest control technician in an important role to reduce the most frequent mosquito bites, and to fight Zika and other Aedes-borne illnesses, should they arise here.

If you missed last week's class, and would like to learn more about control of ATM and its biting cousins, several regional training classes will be offered over the next few months.  Stay tuned here for more information.  

Bombs Away

A highlighted quote in PMP magazine's Buzz Online caught my eye today. Alexis Barbarin is a graduate student at Penn State University studying bed bugs and their effects on low income households. Speaking of her insect study subjects, she noted that,

"If you set off a bomb in your room, [the bedbugs will] just move to your neighbors' rooms. It's like date night for them."

Alex's colorful simile underscores one of the common mis-perceptions of what many people refer to as "bug bombs." The warlike term, bug bomb, does have military origins. In 1943, two Americans, Lyle Goodhue and William Sullivan, designed the refillable spray can that became the ancestor of today's household bug bombs. Goodhue's and Sullivan's portable can enabled soldiers to spray the insides of their tents for malaria-carrying mosquitoes in the Pacific during World War II. Perhaps with the marketing assistance of Raid^® television commercials, people today tend to think of bug bombs (or more accurately, "total release aerosols") as the ultimate in pest control, with an almost uncanny ability to search-and-destroy.

While consumer aerosol generators may flush some insects from shallow hiding places into the open, they are in no way magical in their killing action. Aerosols are most effective at killing flying, or crawling insects on exposed surfaces. Insects inside walls, furniture or even deep in carpet pile are not well controlled with these devices.

The chemicals in aerosol generators are generally short-lived, remain airborne for a limited time and must be carried on air currents if they are to reach into corners and hidden areas in a room. It is unlikely that typical bug bomb products flush and kill many pests who are well protected in furniture, mattresses, behind baseboards and even picture frames, per Alex's bed bug observation. Because of the repellent nature of some of the active ingredients in aerosol generators, if anything insects are likely to be driven deeper into their hiding places or into adjacent rooms, businesses or apartments.

To address another misconception, aerosols are completely different from fumigation. Fumigation involves using a toxic gas, like methyl bromide or sulfuryl flouride, to penetrate food products, buildings or furniture to kill hidden pests. In contrast to fumigants, aerosols consist of very tiny liquid particles that are dispersed into the air via pressurized gas, combustion, or mechanical dispersion. Typical aerosol particles range from 5 to 50 microns in diameter (a typical human hair, by comparison, is approximately 100 microns in diameter). Fumigants, on the other hand, consist of molecules so small that they easily penetrate many substances, including solid wood.

The term "fumigation" should never be used by a professional to mean the same as "spraying" or using a bug bomb. Fumigation is a highly specialized branch of pest control that requires a special license and highly specialized skill and training to perform. Fumigation typically takes place in structures, boats or vehicles that are taped and/or draped with special gas tight tarps.

Another type of application used commonly in pest control is the ULV, or ultra-low volume application. Commercial ULV applicators, like the Actisol and Whitmire Micro-Gen generators, produce particle sizes in the 0.1 to 5 micron range, and are useful for treating voids and cracks not easily reached by sprays or crack and crevice aerosols. Hollow legs of kitchen equipment and voids above ceilings and in walls are excellent places to use ULVs. To avoid problems with repellency, research is being conducted today with low-repellency insecticides in ULV applicators.

Pest management professionals should be aware of the uses and limitations of aerosol and ultra-low-volume applications. Neither are panaceas for tough insect problems. Both should be used in combination with other sanitary and mechanical control methods. And special care should be used to place them directly into pest hiding areas. We want to avoid sending pests on a free date night in the next apartment or business.