Spring Insect Invaders

Paper Wasps. Paper wasps (Polistes sp.) are long-legged, reddish brown to black insects with slender spindle-shaped abdomens. They may have differing degrees of yellowish or brown striping. Paper wasps can become a problem in the fall as the inseminated queens invade homes in search of overwintering sites. But paper wasps can also become a problem in the spring. As temperatures begin to climb, queens that spent the winter in structures become active and fly about. If they have been resting in an attic, wall void or crawlspace, the wasps may be attracted to light coming through a gap in the baseboard or a wall fixture, or around an AC vent and emerge inside the building. Since there are no nests or young to defend, the only real danger of being stung is from accidentally stepping on or pressing against one.

Figure 1. Use an aerosol insecticide
to destroy a paper wasp nest
(Photo: Patty Alder)

Control. Queens that are found indoors may simply be swatted or vacuumed. If a queen does manage to get outdoors and start a nest, a broom may be all that is needed to knock it down. If a wasp nest has had some time to grow and is considered to be a hazard, they are most easily destroyed in the evening with an aerosol insecticide that is labeled for "hornets or wasps" (see Figure 1). 

Clover Mites. Clover mites are occasional invaders that can become a problem in early spring. They are tiny (1/30-inch long), red to reddish-brown, oval-shaped mites. Clover mites, as do other arachnids, have 8 legs. They hold the front pair of legs straight out in front of the head. Many people actually mistake this pair of legs for antennae. Clover mites do not bite nor do they burrow under the skin. They are strictly plant feeders. Hosts include grasses, clover, and dandelion, to name a few.

Most heavy outbreaks occur in the early spring, especially around heavily fertilized lawns. The mites may invade homes and can leave a reddish-brown stain if crushed.

Control. An 18”-24” grass and weed-free zone around the structure’s perimeter can greatly reduce the number of invading clover mites (Figure 2). In addition, treating a 5-10 foot wide area of ground along the foundation, as well as an 18-24 inch wide vertical band of the foundation wall with an appropriately labeled residual liquid insecticide can help.

Figure 2. Placing gravel around the structure
can help prevent clover mite invasions
(Photo: Mike Waldvogel)

 Many plants are actually unattractive to clover mites, including geranium, marigold, zinnia, salvia, rose, chrysanthemum petunia, juniper, spruce, yew and barberry. Planting these non-attractive plants in the weed-free zone will help reduce the number of clover mites around the structure. You may also contact their county Cooperative Extension Center for advice on proper fertilization of your lawn.

The application of insecticides indoors for clover mites is not warranted. Simply use a vacuum cleaner to collect any mites found indoors. Care should be taken not to crush the mites. The vacuum bag should be sealed in a disposable plastic bag before throwing it away.

Kudzu and Brown Marmorated Sting Bugs. We will most likely start to see an increase in the activity of kudzu bugs and brown marmorated stink bugs as well. The stink bugs have a broad host range and are often found on Paulownia (empress tree), Ailanthus (tree of heaven), and crabapple among others, but at this point in the year (particularly in western NC) those host plants have little foliage and cooler weather has kept the bug activity down. And so, a lot of this current activity is simply a response to the warmer temperature and you'll see the insects on non-host sites, such as house siding, cars, etc. Kudzu bugs will be aggregating on almost anything and so you will see them on wisteria and other plants (even if there isn't much foliage), houses, early-planted beans in people's gardens, etc. But even on plants with foliage the insects will simply be hanging out rather than feeding.

Control. Treating the exterior of buildings with a spray insecticide using products containing pyrethroids (such as bifenthrin) may provide termporary relief, but don’t expect any long term relief. There's a big difference between "killing" individual bugs and "controlling" a population of them when these bugs are essentially a "moving target" in terms of where and when they'll show up. In spring, the situation is different than it is in the fall. In the fall, these insects are searching for a way to get into buildings in order to survive the winter. Now, their attention is focused on heading to the great outdoors in search of food and potential mates. So, spraying aggregations (e.g., clusters on a wisteria plant) will kill a bunch of bugs, but more are likely to show up later.

We have information for residential settings at:

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

Figure 3. Boxelder bug adults and nymphs
(Photo: Whitney Cranshaw)

Boxelder Bugs. Adult boxelder bugs are about 1/2-inch long, black with orange or red markings, including three stripes on the area right behind the head. Their wings lay flat over their bodies, overlapping each other to form an ‘X’ (Figure 3). The immature nymphs are 1/16th-inch long and bright red when they first hatch. As they grow and become larger, they become red and black. You can potentially see all stages at any given time during the summer.

Adult boxelder bugs emerge from their overwintering sites in March and early April and feed for about 2 weeks before mating. These insects prefer sunny areas and, therefore, are found most abundantly on trees in a southern exposure and on sides of buildings facing south. The boxelder bug population increases rapidly from middle July to early September.

Boxelder bugs have unusual feeding preferences. Because these insects feed primarily on boxelder and maple seeds, the insects are found on the ground beneath female trees in the early summer before the seeds start to develop. The bugs move into the trees once seeds begin to form. These insects are cannibalistic, particularly when the victim is molting, and they have been reported to feed on other dead or dying insects.

Control. The most permanent solution to a boxelder bug problem is the removal of female boxelder trees from an area, although in most cases this will not be practical or desirable. Outdoors, a pesticide application around the exterior of structures may help reduce the number of invading boxelder bugs. Preventing boxelder bugs from getting into the structure is key. Caulk or otherwise seal any openings the bugs may be using to get indoors. Bugs that enter the home may simply be vacuumed up.

Ground Nesting Bees, by Mike Waldvogel

For those of you who answer pest questions:

You may start getting calls soon from people seeing either small mounds of soil in their yards or reporting "swarms" of bees. Schools and child care facility managers often panic because they think these are swarms that pose a health risk to the children. However, they are most likely the solitary bees such as the "colletids" and "andrenids" that often emerge this time of year.

The bees begin foraging for food and seeking out new nesting sites. This activity will continue for about the next two months, depending on the area of the state and the species of bees. They dig vertical
tunnels in the soil on which they make small side chambers where they provision pollen for their offspring. These bees are "solitary," which means there is no true colony. A lot of the "swarming" that
you see are males and females attempting to pair up and mate (tell people to think of their lawn as a big singles bar for bees). The bees frequently make small mounds in the soil, often where the soil is loose and vegetation may be sparse. You frequently see clusters of these nests, but each nest is made by an individual queen which does the work without the help of workers as occurs in a honey bee nest.

Although the damage can be unsightly with large numbers of mounds in the yard, it is mostly a cosmetic issue. The bigger problem is usually that people walking by panic because they assume that these are swarms of honey bees (or a similar bee) that will likely attack them if they venture too close to "the nest." Turf-nesting bees can sting but rarely do so, since they are not "social" and you don't have a large number of worker bees that trying to protect a nest. There is no "mass attack" as might occasionally occur with a close encounter of the yellowjacket kind (and it's still early in the year
for us to see any yellowjacket colonies out there).

These solitary bees are beneficial and should be left alone if possible. If customers want something done, you can apply almost anything that you typically use outdoors for perimeter treatments. One problem is that the bees often try to dig into the sand in play areas at schools, childcare facilities, etc. Of course, parents and teachers are concerned about stinging incidents, particularly if a child (or teacher) is hypersensitive to bee stings. In those instances, I still strongly discourage any chemical treatment, particularly in sandy play areas where kids come into direct contact with the soil (and which they might get in their mouths as well). However, facility managers have to weigh the safety of children (and staff) and the misinterpretation by the public of ignoring the problem as meaning they lack concern about the children.

If the bees try to nest in a sandbox, a simple solution is to cover it during the day but it will take a few weeks for you to deter most of the bees that show up over time. While the tarping approach isn't always successful, wider areas can be saturated with plain or soapy water which will bring the bees out. Since soap will work as an insecticide to some extent, it may kill some of the bees in the process but I still consider this preferable over the use of conventional insecticides IF people are unwilling to simply ignore the problem. The water-logged soils will hopefully deter the bees but again we're looking at activity that can take place over a few weeks.

Information, including pictures, of these bees and the "damage" that they cause can be found at:

http://www.ces.ncsu.edu/Insects/O&T/lawn/note100/note100.html

Asian Needle Ants Pushing Their Way Through The Carolinas

http://www.newsobserver.com/2013/03/17/2751050/make-way-for-6-legged-samurai.html#storylink=misearch

Structural Pest Workshops - Week of March 4th

The NC Pest Management Association is offering structural pest workshops during the week of March 4th. One CCU in P-Phase and one CCU in W-Phase will be offered. The cost for the workshop is $5 for NCPMA members and $25 for non-members. The workshop schedule can be found by visiting the NCPMA website: http://www.ncpestmanagement.org/. Click on the link for "Spring Workshops".

Kudzu Bugs (AGAIN)

We've had two reports (Scotland County and Union County) that kudzu bugs are moving out of soybean fields and congregating on structures, including homes and school buses. This move out of host plants was anticipated but perhaps not this soon. As to why it's happening now is pure speculation, but favorable weather, particularly early this year, likely contributed to this early exodus as the adult bugs head into reproductive diapause.

The kudzu bug's fall movement indoors is very similar to what we've experienced since the 1990’s with the Asian lady beetle. The major difference between the two insects is that the Asian lady beetle is actually beneficial as a biological control agent, chomping down on aphids and other plant-feeding insects. By contrast, the kudzu bug's primary food source (aside from kudzu) happens to be field crops, such as soybeans, where they can significantly impact yield. So, this pest packs a double-whammy for North Carolinians. 

The kudzu bugs’ fondness of soybeans is one reason why we could see significant numbers of them invading homes and other buildings, even in rural areas. In more urban areas, there are plenty of other hosts such as wisteria and privet. The insects are quite mobile; they are capable of catching rides on wind currents, automobiles, trucks, trains and planes. This helps explain why this pest has managed to spread in from north-central Georgia and through most of South Carolina, North Carolina, and Virginia (plus west into Mississippi) in just about 3 years time. 

At this point, we still do not have anything new to report in terms of recommendations to homeowners and businesses as to how they might address this problem. Kudzu bugs are attracted to light-colored surfaces but that certainly doesn't mean that brick buildings or those with dark-colored siding will escape the bug invasion. While most folks want shortcuts and easy solutions, there simply aren't any when it comes to the kudzu bug. The emphasis still has to be on exclusion because chemical control is still only partially effective and relies primarily on directly targeting the insects that are aggregating on surfaces. Preventive sprays are not recommended - because they simply won't be durable enough to last the weeks during which these insects will be actively seeking overwintering sites. If the situation is severe and you decide that pesticides are warranted, you can choose any of the common exterior insecticides labeled for application to buildings. Use targeted treatments of critical areas: windows and door frames, and some soffits. Be sure to read and follow all label directions carefully. Many of the exterior insecticides contain pyrethroid and new label changes restrict where and how the product may be applied.

If large numbers of kudzu bugs make it indoors, simply vacuum them up. The use of pesticides indoors is not warranted and will be largely ineffective in this case.

Again, we stress exclusion - plugging those holes that the bugs can use to enter homes and
businesses - as job #1.

For more information about kudzu bugs, please visit:
http://www.ces.ncsu.edu/depts/ent/notes/Urban/kudzubug.htm

West Nile Virus in NC, by Mike Waldvogel

Many of you probably saw or read reports about increased incidences of West Nile Virus across the U.S. with the notable exception of a few states, including North Carolina. However, Wayne County has reported a death attributed to West Nile Virus. At this point, there are only a few details being provided about the person which is to be expected due to health records privacy laws. However, the announcement from the Wayne County Health Director’s office (as reported by the Goldsboro News-Argus) described the victim as “elderly."

Only about 1% of people who become infected develop severe illness, and many people may not become sick at all. In cases of people who do develop symptoms (which takes 3-14 days), many of them may not attribute it 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 mentioned above).

West Nile Virus occurs far less frequently in people in North Carolina as compared to other nearby states and it is far less frequent here than other mosquito-borne diseases such as Eastern Equine Encephalitis (EEE) and LaCrosse Encephalitis (LAC). EEE is more common in eastern NC while LAC is found primarily in western NC. Birds are the “amplifying hosts” for the 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 wastewater
collection areas and stagnating catch-basins. You can also find them breeding where water collects after storms and begins to stagnate with the abundant 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 I mentioned a few weeks ago, substantial rainfall (as we have seen recently in many areas) is inevitably going to lead to a rise in mosquito activity and the first response by individuals should focus on disrupting those breeding pools rather than worrying about what to spray in their yard. These were some of the particular points I mentioned previously, but they're worth noting again:

• Bird baths - simply flush them out with a garden hose and you flush out the mosquito larvae 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 (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.
• Remove all of that built-up debris from your gutters. The water and decaying material 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 that cover your boat, grill, 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 your yard.
• Kids' pools - if they're not being used by kids, they're probably being used by the mosquitoes (and maybe some toads) – empty them. The same thing applies to pools (in ground or above ground) that aren't maintained (e.g., pools on abandoned or foreclosed properties).
• Drainage ditches - they're meant to collect storm water 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 matter – 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 (see http://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, particularly when school is not in session. 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.

One other point that I mentioned a few weeks ago - mosquitoes have no concept of property lines. They are simply out there looking for a blood meal whether it's you or your neighbor. Mosquito "control" may be a matter of spraying chemicals to reduce the population below
nuisance levels. On the other hand, mosquito *management* is what is often needed. It is a long-term proactive project that requires a community effort in order to succeed.

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

Mosquito Activity Will Be Increasing, by Mike Waldvogel

Many areas of the state saw significant rainfall last week and that also means we will see a rise in mosquito activity particularly by the Asian tiger mosquito which takes advantage of those small and often inconspicuous sites around your property that fill with storm water and become prime mosquito breeding sites. So, before people start planning a chemical assault on their yards as the solution to their mosquito problems, they need to start with the simpler and more long-term approach of eliminating "collectibles." I don't mean souvenirs; we're talking about all of those objects that collect and retain rainwater for days or weeks. For example:

• Bird baths - simply flushing them out with a garden hose will flush out the mosquito larvae. 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 dispose of them, 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. 

• Remove all of that built-up debris from your gutters. The water and decaying material 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 that cover your boat, grill, firewood, etc. also collect pockets of water that can remain for 1-2 weeks. So make sure you check those frequently and dump out any water that has collected on them.

• 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 your yard. 

• Kids' 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 (e.g., pools on abandoned or foreclosed properties).

• Drainage ditches - they're meant to collect storm water 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.

Many people ask about treating shrubs in their yard. Mosquitoes will rest in these locations, but whether treating them really "controls" a mosquito problem is difficult to determine depending on the species of mosquitoes most prominent in your area. Similarly, people using outdoor foggers will definitely kill mosquitoes, but depending on the time of day/evening that they use it, they may be missing the peak activity of the most common mosquito species found in their area. Two other issues about using outdoor foggers are important. First, safety is critical. Make sure that you are standing upwind from the direction that you are dispersing the fog and wear appropriate protective equipment to prevent the fog from getting into your eyes and lungs or on your skin. Second, know where the fog is going. Some of your neighbors may not actually want chemicals drifting onto their property (particularly if they're outside eating at the time!). The same applies to the automated misting systems that some people have installed on their homes. From time to time, we get reports of companies that offer “mosquito control” whose response to the question of what they are using is simply that it’s something “safe” or “natural” but they won’t actually tell you what the chemical is. Personally, I would steer clear of a company that isn’t willing to tell you what they are spraying (or propose to spray) on *your* property. You have the right to know the identity of the product and if they won’t reveal it, the NC Department of Agriculture and Consumer Services is very willing to “encourage” them to be forthright about their control program.

One other point to remember - mosquitoes have no concept of property lines. Mosquito management takes a neighborhood effort to be truly effective. We have information on mosquito control on the web at http://insects.ncsu.edu/Urban/mosquito.htm.