Tuesday, July 26, 2016

The OTHER clothes moths

This week I received reports of two insects that are sometimes confused with clothes moths or pantry pests. The brown house moth, Hofmannophila pseudospretella, is a common moth pest in the United Kingdom, but much less so in the U.S.  In a paper written in the 1950s, one researcher noted that it probably occurred in small numbers in every private home in Britain, and that few stores or warehouses in Britain were without at least a small population.  The brown house moth specimens I saw on a sticky card this week, however, were the first ones of this moth I've ever encountered in Texas.

Brown house moth on sticky card.  Head to tail, these  
small moths are between 4 and 7 mm long. 
The BHM could easily be mistaken for Indian meal moth based on size.  But wing patterns are different.  Wings are bronzy brown with dark flecks on the forewings.  It is a slow grower with about one generation per year, but capable of becoming abundant under the right conditions.  It appears to require high relative humidity of 80% or more, perhaps accounting for the fact that it is not so common in climate controlled homes here in the U.S.

The diet of BHM is varied, ranging from cereal products to wool and dead insects.  It is readily capable of developing in wheat germ, whole wheat, damaged beans, macaroni, fish meal.  When yeasts were present, it could also develop on feathers and flannel wool.

Woodroofe, a British entomologist who studied the moth over 60 years ago, felt that the importance of this moth in homes was more as a fabric pest than a pest of stored grains.  If this moth is found in a home the most likely source of infestation would likely be in a basement or garage with higher humidity.  Check for pet food, woolen clothing, furs or feathers being stored under damp conditions. Also look in light fixtures with dead insect accumulations, or old bird nests in chimneys or soffits. Sticky traps may be useful in catching some of the moths for identification. If the suspected site of infestation is in an inaccessible void, consider dusting the area with Cimexa or Tri-Die, or other dessicant dust. If given a chance, these little moths can become very abundant.

Household casebearer cases collected from a
home in east Texas.  Note the caterpillar head
emerging from the case on the far right, and the
flattened cases widest in the middle. Photo by
Randy Reeves.
Another interesting insect that I encounter more frequently in samples is the plaster bagworm or household casebearer, Phereoeca uterella.  A close cousin to the clothes moth, household casebearers live inside a spindle-shaped silken case.  University of Florida provides a nice article on this moth, which feeds largely on spider webs.  If that sounds like an odd thing to eat, remember that spider webs are a type of proteinaceous silk, and probably just as nourishing to a clothes moth as silk clothing made from silkworm silk.

Like the BHM, household casebearers thrive in higher humidity conditions.  The cases, like a silk purse, are usually flat in later life stages.  It is most likely to be confused with the casemaking clothes moth, a more frequently encountered pest; but the spindle shape, and flattened case are distinctive.  According to the Florida fact sheet these cases may be found "under spiderwebs, in bathrooms, bedrooms and garages... on wool rugs and wool carpets, hanging on curtains, or underneath buildings, hanging from subflooring, joists, sills and foundations; on the exterior of buildings in shaded places, under farm sheds, under lawn furniture, on stored farm machinery and on tree trunks."  Besides spider silk, the caterpillars have been observed to feed on wool, human hair and dead insects.

I've not heard of any infestations severe enough to require insecticide use with household casebearer. In most cases they seem to be a curiosity more than anything; but a vacuum cleaner to get rid of spider webs would be a good idea to make sure that your casebearers don't decide to nosh on something a little more valuable in the home.

Friday, July 22, 2016

Webinar on mosquito control Monday

Drs. Grayson Brown (top) and
Nicky Gallagher are featured
speakers at next week's Webinar.
Just a short post today about a webinar on mosquito control for PMPs on Monday, July 25.  It's sponsored by PCT magazine and will be held at 1 pm CDT (that's Texas time).  Free signup is available here.  Speakers are Drs. Nicky Gallagher with Syngenta, and Grayson Brown with the University of Kentucky, both excellent speakers and knowledgable in mosquito control technology.

My reason for plugging this particular webinar is its timeliness, in combination with the surprising growth of the mosquito control portion of the pest control industry over the past couple of years.  I was shocked to learn at this spring's National Conference on Urban Entomology that mosquitoes are now big player Orkin's #1 annual residential service offering.  And I was amazed to hear that Arrow Exterminating's mosquito annual revenue went from $39,000 in 2004 to $6.5 million in 2015,with mosquito control customers among their most loyal customers.

So if you service residential accounts and are not yet providing mosquito control services, you might want to check out this offering. All you need is a computer and connection to the Internet. What could be an easier way to grow your business?

Thursday, July 14, 2016

West Nile virus risk high in north Texas

Residual insecticides applied via backpack mist blower
sprayer can provide 3-4 weeks of mosquito control  during
times of peak mosquito activity.
July and August are typically the months of highest risk from west Nile virus, and true to form the past few weeks Dallas and Tarrant counties have seen a major increase in not only mosquitoes themselves, but infections within the mosquitoes.

After the major outbreak of WNV in 2012 in north Texas, some health officials made a decision to use something called the Vector Index (VI) as a form of threshold to ramp up mosquito control efforts.  Based on when human cases started to soar in 2012, and on suggestion from the CDC, a VI of 0.5 was determined to be a good threshold to consider going from ground based spray efforts to aerial spraying.

Two weeks ago the VI exceeded that threshold in both Dallas and Tarrant counties.  Both counties publish very interesting reports, available to the public, that include graphs to show  the latest mosquito counts and VI numbers.  To see the trends in Dallas and Fort Worth areas, check out the graphs below.  In the first graph, the Vector Index is the heavy red line.  Last week it exceeded the 0.50 threshold, although there was a drop this week. Note also the numbers of mosquitoes this summer (red bars) compared to average trap catches in 2012 (for the past four weeks, higher than 2012 averages shown by the blue bars). In Tarrant County (Fort Worth and surrounding communities) the VI (green line with triangle points) was likewise up last week, over 0.60 (new data is not yet published).  Note that the most recent 1-2 data points are preliminary estimates and may change as all the data is calculated.

These data are why there is discussion about aerial spraying this week.  In 2012 the number of human cases of WNV in Dallas county reached almost 400, and there were 19 deaths attributed to WNV. Serious business. Last week DCHHS issued a health advisory to the public, and this week the Dallas County commissioners voted to authorize the health department to prepare for possible aerial spray operations should conditions warrant.  

Where does all this leave the PMP who provides residential mosquito control service?  Municipal mosquito spraying actually complements, rather than replaces, mosquito control work on the ground done by professionals.  Aerial spraying generally provides better coverage of the tree canopy where WNV carrying mosquitoes (Culex quinquefasciatus in north Texas) live and mostly feed. Municipal truck mounted ULV sprays provide some control of lower level mosquitoes (Aedes mosquitoes that potentially transmit Zika and dengue fever, among other diseases), but they typically do not provide high level control in backyards or areas protected from spray coverage.  In that sense, the best control of Aedes mosquitoes is accomplished by your boots on the ground, looking for and treating or eliminating mosquito breeding sites, treating doorways, and treating shrubbery and other mosquito resting sites that are difficult to reach from the street.

As you and your technicians visit mosquito control customers this summer, keep in mind that you carry some of the most effective tools in the war against mosquitoes.  This summer, with Zika fears and WNV threats, what you do is more important than ever.

New Zika Resources for the Public

Hiring a professional is one way that the public
can help reduce mosquito biting risk around the home.
I was asked a few weeks ago if the collective "we" (meaning the whole state of Texas) were going to be ready for Zika.  My answer was a cautious, "I think so".  If we're not, it at least it won't be for lack of trying.

Zika is a much different disease than West Nile virus. It has different vectors, mosquitoes that prefer to feed on humans over any other animal (unlike WNV mosquitoes, which mostly feed on birds).  It is also very difficult to detect in wild mosquito populations.  The mosquitoes are more difficult to control with spray trucks, so responding to local cases is going to depend more on public cooperation.

Unlike WNV, Zika is virtually undetectable in the blood supply, as there is no approved way to screen newly donated blood to see whether it has the Zika virus in it. If Zika does make it into the country, it will also potentially affects more people.  Any family with members of childbearing age will need to be on high alert. The CDC recently released its response plan for Zika.  It's assumptions are sobering:
  • Travel-associated and sexually-transmitted cases will continue to occur and are likely to increase. (we just don't know how much!)
  • Local transmission (spread) of Zika virus in US territories and affiliated Pacific Island countries is ongoing.
  • Neither vaccines nor proven clinical treatments are expected to be available to treat or prevent Zika virus infections before local transmission begins nationwide.
  • The ability for mosquito control efforts to reduce infection risks may be limited, as has been the case with similar viruses, such as dengue and chikungunya.
The entomology department, and especially my colleague Extension entomologist Dr. Sonja Swiger, has been busy in recent weeks trying to figure out how to best arm everyone with the best information on how to prepare for the "Summer of Zika".

As part of the effort, some new fact sheets from Texas A&M AgriLife Extension are now available to answer some of the more common Zika questions. These may be useful for your customers who are worried about mosquitoes and how to protect themselves.  The DIY fact sheet talks about the different consumer-oriented treatment options, including hiring a professional.