Mosquitoes and West Nile Virus

Many of you may have seen the report that someone in NC has died from West Nile Virus (WNV). Although the NC Department of Human and Health Services does not release patient-specific information in these situations, the person was subsequently identified by his family as being a 76 year old man in Durham County.

Only about 1% of people who become infected develop severe illness, and many people may not become sick at all. The symptoms of West Nile Virus can take 3-14 days to present themselves. Therefore, many people may not attribute their illness to the virus until it becomes severe. Among people that develop severe illness (i.e., excluding those individuals who exhibit minimal or no symptoms), the mortality rate ranges from about 3% to 15%, with the rate being highest among the elderly (as likely the case here).

As we've seen in previous years, West Nile Virus occurs far less frequently in people in North Carolina as compared to other nearby states. We did not have a human case of WNV in 2014 and only about three in 2013. Those numbers are not intended to trivialize the fact that people were affected (some fatally). It's just a matter of making sure that people don't panic about the disease and just use common sense. West Nile Virus is far less frequent here than other mosquito-borne diseases, such as Eastern Equine Encephalitis (EEE) and LaCrosse Encephalitis (LACE). EEE is typically more common in eastern NC and occurs most commonly in horses that were not inoculated against the disease.

Birds are the "amplifying hosts" for West Nile virus, which basically means that infected mosquitoes transmit the virus to birds which are in turn bitten by other mosquitoes which acquire the virus and spread it to even more birds. Some mosquitoes species feed primarily on birds but the species that will readily feed on both birds and mammals are the ones that pose the risk of spreading the disease to people. The mosquito species that transmit West Nile Virus tend to breed in waste water collection areas and stagnating catch-basins. You can also find them breeding where water collects after storms and begins to stagnate with an abundance of organic matter present. So, one obvious approach for residents is to make sure that they clear stagnating water sources on their property. It doesn't matter if this water is on a 1000-acre farm or on a 0.1-acre home lot, water that collects and stagnates has the potential to become a mosquito breeding site. Across most of North Carolina, the Asian tiger mosquito remains our most common pest species and it will exploit similar pools of stagnating water on the ground and in man-made objects.

As always, rainfall will dictate a lot of ebbs and flows of mosquito activity but with a multitude of urban water sources as breeding grounds, we will continue to see mosquito activity continuing into the early fall as long as temperatures are favorable (although the shortening day lengths and declining temperatures will send some mosquitoes into diapause). Although pesticides have their use in mosquito management, the first response by individuals should focus on "source reduction" (i.e., disrupting/eliminating those breeding sources rather than worrying first about what to insecticide to spray).

Follow these tips below for a good source reduction program:

• Bird baths - simply flush them out with a garden hose, and the mosquito larvae is flushed out in the process. Plus, the birds will appreciate the fresh water. For horse owners with water troughs near stalls or out in pastures, one option is to use a product such as "Mosquito Dunks," which contain the bacteria Bacillus thuringiensis israelensis, which kills the mosquito larvae (but not the adults). Although you can use them in outdoor water bowls for pets, it is far simpler (and better for your animals) if you "tip and toss" the water from the bowl and replenish it with fresh water daily.

• Old cans, tires, etc. - empty them and get rid of them (legally, don't simply toss them along the highway to become someone else's problem).

• Outdoor flower pots - empty the water from the dishes/trays underneath them. Your plants have plenty of water without the overflow. This also helps reduce fungus gnat problems in the plant soil.

• All of that built-up debris in your gutters that you've been planning to clean out? It's time to actually do it and get rid of the water and decaying material that attract mosquitoes.

• Rain barrels - if you collect water from your gutters or some other system, make sure the barrel is screened to keep out debris and mosquitoes

• Tarps covering boats, grills, firewood, etc. also collect pockets of water that can remain for 1-2 weeks.

• The bed of that '57 Ford pickup that you've been "restoring" for the last 25 years can collect water particularly if the tailgate faces uphill in the yard.

• Kiddie pools - if they're not being used by kids, they're probably being used by the mosquitoes (and maybe some toads). So, empty them. The same thing applies to pools (in ground or above ground) that aren't maintained. In some of our western states where drought has been a major issue, swimming pools have become mosquito magnets (and the swimming pool owners have become the object of attention for emerging female mosquitoes looking for a blood meal).

• Drainage ditches - they're meant to collect storm water runoff temporarily. Keep them free of debris so that water flows and has time to filter into the soil.

• Decorative fish ponds can be a source of mosquitoes if they contain a lot of vegetation that provides hiding places for the mosquito larvae. "Mosquito Dunks" are an option here.

• Tree holes - when limbs fall off trees, the remaining hole in the trunk can collect water. Flush that out or put a small piece of a mosquito dunk into it.

Another critical issue - personal protection. The majority of mosquito-borne disease incidences, whether they're human or equine, are due to a lack of personal protection. Horse owners need to spend the time and money to get their horses vaccinated against EEE. For us two-legged creatures, we simply need to take precautions when we're outdoors for work or recreation. If it's too uncomfortable to wear long-sleeved shirts and long pants, then cover all exposed areas of the skin with an insect repellent (seehttp://insects.ncsu.edu/Urban/repellents.htm). A few other important points about using repellents:

• Do not put repellent on skin that will be covered by clothing.

• Children spend a lot of time outdoors even when school is back in session because the weather has been favorable. The greater the amount of time spent outdoors can increase the likelihood of getting bitten by a mosquito (and potentially a higher likelihood of being bitten by an infected mosquito). Before applying a repellent to a child, read the label carefully to make sure that it contains concentration appropriate for use on children.

• When using repellents on children you should apply the product to your hands and then rub it on their arms, legs, neck, etc. If you allow your child to rub repellent on their arms and legs, they need to wash their hands immediately afterwards because they will inevitably forget and either rub their eyes or stick their fingers in their mouths.

In terms of yard treatments for mosquitoes, the idea is to treat mosquito resting spots on the lawn and surrounding landscaping. These treatments can help reduce mosquito populations and are certainly a choice for individuals to make. With regard to fogging outdoors for mosquitoes (e.g., with the hand-held or backpack fogging machines available at hardware stores), these pieces of equipment produce a fine aerosol mist. So, bear in mind a few things if you decide to go that route:

• Spray when there is little (if any) wind. Otherwise, the chemical simply drifts off your property rapidly and may not kill as many mosquitoes are you expect.

• Remove or cover children's toys, pet water & food bowls, barbecue grills, etc.

• Avoid spraying flowering plants during the day when bees and other pollinators are out there. We're already losing enough honey bees and you don't need to contribute to the toll. 

• Stay upwind of any application that you're doing and take precautions by wearing proper Personal Protective Equipment (PPE) - long-sleeved shirts, long pants, hat, goggles, and preferably some respiratory protection. 

• More importantly, watch out for drift off of your property. The chemical may end up on someone else's property, whether that's private property or a park, school, or some other public property. Your neighbor's may or may not be receptive to the chemical mist and you need to be aware in particular what is going on at the adjoining property so you don't contaminate people/children, pets, food, honey bee hives, etc. 

And along that line, one other very important point - mosquitoes have no concept of property lines. They are simply out there looking for a blood meal whether it's you or your neighbor. Chemicals may knock down mosquito populations right now and provide some "control." However, mosquito management is what is really needed and that requires a proactive community effort in order to succeed. "It takes a village" applies to mosquito management and you only need one "village idiot" to make that program be unsuccessful. Communication and cooperation are as important (or more important) to make mosquito management work.

We have information on mosquito control on the web at
http://insects.ncsu.edu/Urban/mosquito.htm.

Why Cockroaches Die on Their Backs

Below is a link to an article featuring Dr. Coby Schal with NCSU's Department of Entomology.

Coby Schal is a professor of entomology at
North Carolina State University

http://www.newsobserver.com/news/technology/article27927940.html

What's That Smell? The True Odor of the Odorous House Ant

You’ve probably told many clients that the odorous house ant smells like rotten coconut when it’s crushed, after which your client inevitably give you a “look” – one that tells you they think it’s disgusting that you readily squish ants! 

While the freshly crushed odorous house ant does produce a definite odor, describing it as “rotten coconut” never said a lot to me, namely because I have never smelled a rotten coconut! I have always thought the odorous house ant produced a clean smell, almost like glass cleaner, with more of a “punch.” In an effort to provide more accurate information on just how the odorous house ant smells, Clint Penick and Adrian Smith conducted a recent study investigating the volatile compounds released by the odorous house ant and the items most commonly associated with their scent. 

The vast majority of online sources identify the odor of the odorous house ant as “coconut-like” (Fig. 1A). This ran counter to the results of a smell test that Penick and Smith conducted as part of their study. In the smell test, participants most identified the smell of a freshly crushed odorous house ant as “blue cheese,” followed by “other” as a close second (Fig. 1B). The most common write-in candidate for “other” was cleaning spray (very similar to way I have always described the smell of odorous house ants!).

When Penick and Smith also used gas chromatography-mass spectrometry to determine the exact chemical composition of the odorous house ant scent. They found that the major component of the odorous house ant scent was a methyl ketone (Fig. 2) that has actually been identified in other ant species as well. As in turns out, the most prominent compounds associated with blue cheese are also methyl ketones. No methyl ketones were found in fresh coconut. Once coconut turned rotten, however, it released the same methyl ketones found in blue cheese. Interestingly, the microbes that turn coconut oil rancid – Penicillium mold – are the very same microbes used to make blue cheese!

So, what exactly IS that smell? According to Penick and Smith’s results, the odorous house ant odor points to blue cheese, with a cautious nod to rotten coconut. They emphasized cautious because it’s not the “coconut” in rotten coconut that smells like the odorous house ant, but the “rotten.” To sum up, odorous house ants do not smell like coconuts. They smell like blue cheese. Or you could say that they smell like coconuts that have been colonized by Penicillium mold that causes the coconut oil to produce an odor similar to blue cheese.

EPA Publishes Proposal To Mitigate Exposure to Bees From Acutely Toxic Pesticide Products; Notice of Availability

On Friday May 29, the EPA published a proposal to mitigate exposure to managed bees from pesticide products from foliar applications. The EPA’s proposal would prohibit the foliar application of acutely toxic products (neonicotinoids) during bloom for locations with bees on-site and under contract. Current neonicotinoid product labels contain a 48 hour notice exception, which will be removed from the label. This proposal was detailed in the President’s National Strategy to Promote the Health of Honey Bees and Other Pollinators released last week. The proposal is very limited to foliar applications when managed pollinators are on the property under contract. 


https://www.federalregister.gov/articles/2015/05/29/2015-12989/proposal-to-mitigate-exposure-to-bees-from-acutely-toxic-pesticide-products-notice-of-availability

The Buzz on Spring Household Pests

Carpenter Bees

Carpenter bee activity is increasing with the warmer temperatures. Although carpenter bees resemble bumble bees, the two can be readily distinguished from one another because carpenter bees have shiny bare abdomens, while bumble bees have yellowish hairs on their abdomens. The male bees are easy to identify because they have white spots in the center of their head (between their eyes) and they are typically seen hovering around prime real estate (from a carpenter bee's perspective) watching for the girl bee of their dreams and chasing off rival males at the same time. Males bees do not sting but their aggressive behavior can intimidate people.

After mating, the female bee goes hunting for a new place to build a nesting gallery. Choice locations include wooden porch rails and balusters, wooden planks and solid wood siding (even "repellent" woods such as cedar). The females handle the workload and excavate a nearly perfectly round hole and gallery that typically follows the wood grain. She then makes a ball of pollen, sticks it into the gallery and deposits an egg before constructing a partition of chewed wood debris and other materials. She then repeats this process until the gallery is furnished with each of her "children" having their own room (but no internet or cable TV). At that point, the females die and so for most of the summer, no activity is seen. The offspring will emerge in the late summer/fall and hang around before finding a sheltered location (like an abandoned gallery) where they pass the winter.

We still do not have any pesticides that provide long-term protection of wood for the duration of the bees' activity. It's also difficult economically and from a safety perspective to spray all of the exposed overhead wooden areas to protect them from the bees. We still recommend the tried and true method of dusting individual holes with a pesticide dust (some wettable powder formulations are labeled for this use, too) and then seal the holes (to keep out moisture).

We have additional information online at: http://insects.ncsu.edu/Urban/carpenterbees.htm

Paper Wasps

Overwintering paper wasps (Polistes spp.) queens are starting to become active. This is another situation where insects show up indoors and people think that they're entering their homes from outside. For the most part, the wasps have spent the winter in wall voids, attics, and crawlspaces. As a result, as the weather warms and they become active, some of the wasps accidentally stray indoors (instead of heading to the great outdoors) and people assume that there is an active nest in their wall, attic or crawlspace. The wasps are usually slow moving (you would be too if you had slept all winter!) and simply buzz about looking for a way outside but that creates this appearance of being aggressive. Although these wasps can sting, their main goal is finding:  a) food; and b) a place to build a nest. They are an easy target for a rolled-up newspaper!

The wasps that do make it to the outside (or were hiding out under bark, tarps, etc.) will often be seen hovering around the house exterior, particularly near chimneys and other vertical objects. This attraction to vertical objects often makes cell phone towers and similar structures the object of their attention which can be disconcerting to workers hundreds of feet up servicing these structures. Hereto, people assume that there is already an active nest and simply can't find it. Spraying broad areas of house siding, deck, etc. is not going to stop this activity.

The wasps are busy scoping out perspective nesting sites. If you have clients concerned about getting stung, wasps can be treated with a wasp & hornet spray that propels the chemical about 15-20 feet. Exercise caution as you spray overhead.

Also, remind people that despite their reputation for stinging, these wasps are actually beneficial and prey on caterpillars and other insects that would likely be chomping down on their flower or vegetable garden later in the year. So, focus on nests that may pose an imminent hazard. Trying to eradicate every wasp is neither practical or (more importantly) environmentally sound. For more info, please visit:

http://insects.ncsu.edu/Urban/paperwasp.htm

March Madness (Insect Style), by Mike Waldvogel

Termites. It's finally spring (at least in theory!). Rain earlier last week coupled with our warmer temperatures are a great prelude to termite swarming. Most of what people see are termite swarms outdoors which, as I have said in numerous past years, is just nature's way of reminding you that termites are all around you. It does NOT mean that you should spray your yard (which won't really help anyway); nor does it mean you need to have your house treated. HOWEVER, if you haven't had your house treated or inspected in recent years, then having it inspected might be a good idea. You can do the inspection yourself if you're confident (i.e., you're sure you know what to look for) and careful about checking the foundation (crawlspace and exterior) which may require pushing back fiberglass insulation so you can check wood framing that rests on the foundation. You should also check "critical areas" around plumbing. Calling a professional to inspect your house has its obvious advantages in that pest management professionals can probably be efficient in inspecting your home. Remember, a termite treatment isn't needed unless you find evidence of termite activity, although some people may decide to act proactively and have their house treated.

On the other hand, if termites swarm indoors, then you most likely have an infestation that should be addressed within a few weeks. Bear in mind, that even if you find swarmers, you don't need to rush on making a decision. Call a few companies, and get their assessment of any problem and an estimate of the cost to treat the house (if needed). Depending on the size and nature of your home's construction, termite treatments range from $500 to $2000 plus. Take the time to make an informed, well-founded decision about the type of treatment and warranty being offered. Damage repair warranties sound great but read the contract and understand that the warranty excludes "existing damage" which means damage that is identified as already present at the time of their initial inspection (this should be noted on the diagram they present to you with a proposal to treat the house) OR damage that wasn't visible at the time of the inspection (e.g., inside a wall) and there are no live termites present when the damage is discovered. While this may sound unfair, it's simply a matter that the company can't be accountable for damage that wasn't visible/accessible when they initiated the warranty and so there's no way to know when it occurred.

Serious termite damage takes years to occur. Many companies can take 7-14 days to get around to treating a customer's house during peak termite activity. So, if your floor was going to fall in because of termite damage, it would happen regardless of whether you have the house treated today or in 2-3 weeks. However, if there is significant structural damage due to termites, then you may want to do repairs before proceeding with any treatment in case the repairs require any soil excavation (which could also disrupt any termite treatment in the process).

We have more information about termites at: http://insects.ncsu.edu/wood.htm

Mosquitoes. You may be wondering how the cool/cold wet weather impacts pests, such as mosquitoes, and whether that means we'll have fewer mosquitoes. You will see mosquitoes out there even with some of our projected cooler temperatures, but those mosquitoes are species that overwinter as adults and respond more quickly to rises in air temperature.

In most of NC, our major problem is the Asian tiger mosquito; it spends the winter as an egg, which means it needs water (for the larvae to use as a habitat), plus temperature (water and air temperature), and an increasing day length to trigger activity. So, we still have time before we start seeing any real problems. However, this is the time of year to be thinking "habitat modification," which simply means a bunch of things you need to add to your list of spring chores:

• Get rid of (or repair) those objects that collect water. Fix tarps covering boats, cars, etc. so they don't collect water. If you're going to use rain barrels to collect and conserve water for use in your garden, make sure they have been cleaned of all leaf debris and other organic matter and that you cover them with screening to keep out debris and exclude mosquitoes.

• Clean out your gutters which trap water, along with leaves and organic debris, that attract mosquitoes (for egg-laying purposes).

• Clean out drainage ditches in front of your property. They're meant to catch and drain run-off, not become breeding pools for mosquitoes.

• And convince your neighbors to do the same because mosquito control takes a community effort. Mosquito control is a good example of the phrase "It takes a village" because everyone has to participate and it only takes one proverbial "village idiot" to make the collective effort fail.

Ticks. We're still a few months away from "tick season" but that doesn't mean some won't start wandering about looking for a meal. Mow back any taller weeds on the fringe of your yard to cut back on habitat favoring field mice and other hosts of the common ticks that we have here. When you're finished mowing/trimming back those weeds, don't forget to check yourself over for ticks. Better safe than being tick food!

Ground Bees Active But Pose No Threaten to People or Yards, by Steve Frank, NCSU Extension Entomologist

As I write this my front yard is abuzz with small bees. Many are flying around just above the ground while others fly back and forth to redbuds and camellias gathering pollen.

Although these bees do not generally sting, I watch as mothers nervously cross the street with strollers. Neighbors pass by and comment "Watch out for all those fire ants" referring to the small mounds that dot my sparsely vegetated lawn. Others offer suggestions on how to rid myself of these dangerous beasts that are "tearing up your lawn."

The bees I am watching are ground nesting bees in the family Andrenidae. All the species in this family are solitary and nest in the ground. Solitary means they do not maintain vast hives with hundreds of workers like honeybees or yellow jackets. A single female bee builds the nest by burrowing into the ground. She prepares larval cells where eggs will be laid. Mothers provision each brood cell with a mixture of pollen and nectar (called bee bread) that serves as food for young larvae. After laying an egg she closes the brood cell and starts another. After completing several brood cells the mother will seal the entrance and leave the nest to begin a new nest. After a few weeks she will die leaving the next generation safe in the ground.

Bee emerging from its mound (Photo: S.D. Frank).

In the spring, bees complete development and emerge as adults that dig their way out of the ground and forage for pollen and nectar to provision their own nests (see photo above). The visual spectacle of these bees is produced largely by males who swarm over nests trying to mate with newly emerged females. The other noticeable aspect of these bees is the small mounds of dirt excavated for each nest.

Hundreds of small mounds created by bees.

Hundreds of small mounds and swarms of bees often trigger calls to exterminators or landscape professionals (see photo at right). Homeowners fear that they will be attacked and stung as they bend over to pick up the paper and they believe that the bees are actively damaging their yard and want them gone. This is not the case.

An ovipositor is the organ female insects use to insert eggs into substrates such as leaves, wood, soil, other insects, or in our case brood cells. In social insects such as honeybees, most of the females are workers that do not mate or lay eggs and thus have no need for an ovipositor. However, they do need to protect the nest from invaders. Therefore, the ovipositor of these social species has evolved into a stinger to ward off threats.

With this in mind it is easy to understand why the threat of being stung by the ground nesting bees in my yard is so small. First, the bees swarming around are mostly males. Males don't lay eggs and thus do not have an ovipositor, modified or otherwise. The female bees are responsible for all aspects of nest construction and provisioning and are busy digging and foraging. Since the ovipositor of ground nesting bees is necessary for laying eggs, it is not well developed as a stinger, if at all. I won't say that you will never be stung because this would encourage some fool to torment bees until they proved me wrong. However, I have handled these bees quite a bit and have never been stung (see photo below).

Bee held safely for a portrait (Photo: S.D. Frank).

These bees prefer to nest in dry, sparsely vegetating areas. Therefore, if you have bees nesting in your lawn it is because the grass is thin and the soil is dry. The bees don't make it this way, they just take advantage of the conditions. If anything the bees are providing a valuable service by aerating the lawn!

The behavior and habitat preference of these bees leads us to the most promising ways to reduce their abundance in a particular yard. First they like dry soil they can dig nests in. Therefore, irrigation over the 3-4 weeks bees are active will encourage them to find other nest sites and reduce their abundance the following year. In addition, they like thin lawns with plenty of bare spots. Thus, you can take measures to improve the density of your grass to make it less appealing to bees. Native bees are an important part of ecosystems and food production. We should take steps to protect these bees or at least use non-lethal means to encourage them to nest somewhere else.