Bed Bug Infestations Can Raise Histamine Levels in Infested Homes

Histamines produced by bed bugs can persist for some time after bed bugs have been eliminated. (Photo: Matt Bertone)

A new study from North Carolina State University shows that histamine levels are substantially higher in homes infested by bed bugs than in uninfested homes. The study also found that these histamine levels persist for months – even if the bed bugs have been eliminated from the home. These findings suggest that bed bugs may be more than just a mere nuisance pest. The bed bug-produced histamines could pose a serious health risk in the indoor environment.

NC State post-doctoral researcher Zachary DeVries and colleagues from NC State and the N.C. Dept. of Health and Human Services conducted a Raleigh-based study to compare histamine levels in homes with and without bed bug infestation. The researchers also evaluated the persistence of histamine following bed bug eradication.

“Histamine levels in bed bug infested homes were at least 20 times higher than histamine levels in homes without bed bugs,” DeVries said. “And these levels didn’t decrease much three months after treating the infested homes with heat and insecticides.”

Histamine was recently identified as a close-range aggregation pheromone component in bed bug feces. Exposure to histamines in the environment can provoke allergic responses and asthma. High concentrations of histamine can readily become airborne and represent the major route of entry of allergens into the airway, as documented in studies correlating cockroach allergens in settled and airborne dust. The potential health risks associated with bed bug-produced histamine might rival those associated with other indoor pests, namely cockroaches and dust mites.

Using a Raleigh apartment complex as a study site, the researchers collected the household dust in apartments with bed bugs and those without. Those apartments with bed bug infestations had substantially higher histamine levels in dust than apartments with no evidence of bed bugs as well as “control” apartments some miles away that had no history of bed bug infestation.

The researchers also tracked histamine levels over time after having infested apartments professional heat treated. Histamine levels did not decline significantly three months after treatment, showing the chemical’s capacity to persist despite extreme heat.

“A combination of heat treatment to eradicate bed bugs and rigorous cleaning to eliminate some of the household dust could be a way to reduce these histamine levels; we’ll do future testing to bear that out,” DeVries said. “We’ll also further investigate the effects of histamine in an indoor environment, including chronic exposure to histamine at low levels.”

The research appears in PLOS ONE. Coby Schal, Blanton J. Whitmire Professor of Entomology at NC State, co-authored the paper along with research specialist Richard Santangelo. Alexis Barbarin of the N.C. Dept. of Health and Human Services also co-authored the paper.

Funding for the work came from the U.S. Department of Housing and Urban Development, the Alfred P. Sloan Foundation, the National Institute of Environmental Health Sciences, and NC State’s Blanton J. Whitmire endowment.

Rodent-Proofing for Winter

Winter months are rodents’ most active time for entering structures as they search for food and shelter from cold temperatures. Now is the time to begin taking steps to rodent-proof structures, both inside and out.

Keep them out! Remember, mice can squeeze through an opening the size of a dime or larger, while rats can get through openings quarter-sized or larger. Locate and seal up any gaps on the building exterior. Depending on the size of the opening, screen, sheet metal, steel wool, or copper scrub pads may be used to seal openings. Caulk may be used in some cases, but may not be as long lasting. Make sure all doors and windows tight fitting with weather stripping. Exterior doors should have door sweeps installed.

Figure 1. Debris and other clutter around buildings can harborage rodents (Image: Mike Waldvogel, NCSU).

Don’t give them a place to hide! Reduce or eliminate unnecessary clutter, both indoors and outside. Keep potential shelters such as piles of wood, bricks or stones away from the foundation of your house to discourage rodents from setting up camp right outside (See Figure 1). Rooms or closets with lots of clutter can also provide hiding places for rodents. A little organization goes a long way in eliminating those potential homes for rats and mice.

Figure 2. Mouse damage to a bag of grass seed (Image: Mike Waldvogel, NCSU).

Don’t feed them! Store susceptible food items in sealed, pest proof containers. This includes the foods we eat – like cereal, grains, and rice – as well as pet food, birdseed, and even grass seed (see Figure 2).

Do some landscaping! Rodents can gain access to buildings by climbing across tree limbs and entering the attic or eaves. Trim back trees and shrubs so they are not in direct contact with the foundation so that you can easily spot and address new points of entry that develop.

Taking the steps outlined above can help you make it through the winter months without unwanted guests!

 

 

Managing Millipedes In and Around Homes

Millipedes are common occasional pests that sometimes invade buildings, particularly during very hot, dry weather, or after heavy rainfall. Millipedes do not bite, sting, or transmit diseases, nor do they infest food, clothing or dry, structurally sound wood. Therefore, they are considered more of a nuisance pest, although they can give off an unpleasant odor.

Photo: David Cappaert, Bugwood.org

Millipedes vary in both color and size. The species that most commonly invades buildings is referred to as the “garden millipede,” which is brownish-black in color and about an inch long (see photo at right). When disturbed, millipedes often curl up into a “C” shape and remain motionless. Some people confuse millipedes with centipedes, which look somewhat similar. However, centipedes have only one pair of legs per body segment, while millipedes have two pair of legs per body segment. Centipedes also tend to move about more quickly than millipedes.

Millipedes pass the winter primarily as adults and lay their eggs in the soil in the spring. Individuals may live for several years. Millipedes are attracted to dark, cool, moist environments that are rich in organic matter, such as compost piles, heavily mulched areas, rotting logs, or the soil under logs and stones. They usually go unnoticed because they live in these relatively hidden habitats. Millipedes are scavengers, feeding primarily on decomposing vegetation, but occasionally they will damage soft-stemmed plants in gardens.

Major nuisance problems usually occur when the conditions become too hot and dry and the millipedes move to find moisture, or else when it’s too wet and water-saturated soils force them to the surface and higher ground where they often end up on concrete slabs, foundations and siding. Millipedes may also migrate in the fall, presumably in search of overwintering sites. All of these activities result in millipedes invading crawl spaces, basements, and other areas of buildings. Common points of entry include door thresholds (especially at the base of sliding glass doors, garage doors, etc.), expansion joints, and through the voids of concrete block walls. Frequent indoor sightings of these pests usually means that there are large numbers breeding outdoors in the lawn, or beneath mulch, leaf litter or debris close to the foundation. Millipedes do not survive indoors for more than a few days (more likely just a few hours) unless they can find suitable moist conditions.

Managing Millipedes

Emphasis should be placed on reducing conditions and access points favorable to millipede invasions:

Minimize Moisture, Remove Debris – the most effective, long-term measure for reducing entry of millipedes (and many other pests) is to reduce excess moisture and hiding places, especially near the foundation:

Remove leaves, grass clippings, heavy accumulations of mulch, wooden boards, stones, boxes, and similar items laying on the ground beside the foundation. This does not mean you can’t have mulch around the foundation; simply keep it 6-12″ away from the wall. Consider using an inorganic mulch, such as gravel, which will drain better (see photo at right).

Prevent water from accumulating near the foundation, in basement walls or in the crawl space. Keep gutters and down spouts free of debris and use either splash guards or perforated pipe to reduce puddling. Homes with poor drainage may need to have foundation drains installed, or the surrounding ground contoured or sloped to redirect surface water away from the foundation.

Repair leaking exterior water spigots and prevent water from puddling where there are drip lines from air conditioning units. Reduce the humidity in crawl spaces and basements by providing adequate ventilation, sump pumps, polyethylene soil covers, dehumidifiers, etc.

Since millipedes thrive in the moist, dense thatch layer of poorly maintained turf. De-thatching the lawn and keeping the grass mowed should make the lawn less suitable for millipedes. Over-watering may also contribute to millipede problems.

Seal Pest Entry Points
Seal cracks and other openings in the outside foundation wall, and around the sills of doors and basement windows.
Install door sweeps on all exterior entry doors, and apply caulk along the bottom outside edge and sides of door thresholds (see photo at right).
Seal expansion joints where outdoor patios, sunrooms, and sidewalks abut the foundation. Expansion joints and gaps should also be sealed along the bottom of basement walls on the interior to reduce entry of pests and moisture from outdoors.

Chemical control

Application of insecticides along baseboards and other interior living areas of the home do not really stop millipede invasions. Once indoors, millipedes end up in kitchens, living rooms, etc., and soon die from a lack of moisture. Remove them with a vacuum cleaner or broom.

Applications of insecticide outdoors may help to reduce inward invasion of millipedes and other pests. Treat along entryways, around crawl space doors, foundation vents and utility openings, and up underneath siding. Perimeter sprays (shown at left) may also help but are rarely 100% effective in stopping the millipedes. Pesticides labeled for outdoor use around homes, such as products made by Bayer, Ortho, and Spectracide may be purchased from local hardware stores. The key to successful chemical control is spray volume; i.e., that amount of diluted chemical that you apply over an area. The spray must penetrate the soil, not simply lightly coat the surface. The best means of application for homeowners is a garden hose attachment. Treat a 2-5 foot wide area of ground along the foundation in mulched, ornamental plant beds and grassy areas, as well as an 18-24 inch wide vertical band of the foundation wall.

When treating outdoor areas, remember these important points

Spraying mulch is ineffective because the chemical can bind to the mulch and not penetrate to the soil. Heavy accumulations of mulch and leaf litter should be raked back from the foundation first to expose millipede hiding areas and allow the pesticide to penetrate the soil more readily.

Keep children and pets away from treated areas until the chemical dries (or longer if specified on the product label).

Watch out for pesticide drifting and contaminating toys, swimming pools, and other objects, such as grills.

Pest information and control recommendations presented here were developed for North Carolina and may not be appropriate for other states or regions. Any recommendations for the use of chemicals are included solely as a convenience to the reader and do not imply that insecticides are necessarily the sole or most appropriate method of control. Any mention of brand names or listing of commercial products or services in the publication does not imply endorsements by North Carolina Cooperative Extension nor discrimination against similar products or services. All recommendations for pesticide use were legal at the time of publication, but the status of pesticide registrations and use patterns are subject to change by actions of state and federal regulatory agencies. Individuals who use chemicals are responsible for using these products according to the regulations in their state and to the guidelines on the product label. Before applying any chemical, always obtain current information about its use and read the product label carefully. For assistance, contact the Cooperative Extension Center in your county.

Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Spring Pests Abound

Figure 1. Clover mite. (Photo: Rayanne Lehman, Pennsylvania Department of Agriculture)

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 (Figure 1). 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). Treat 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.

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

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 recommend that your customers contact their county Cooperative Extension Center for advice on proper fertilization of their lawns.

The application of insecticides indoors for clover mites is not warranted. Your customer should 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.

Carpenter Bees. Like other bees, carpenter bees are beneficial in that they pollinate crops and home gardens. However, homeowners are often frightened about being stung by the carpenter bees as they hover around their homes and other wooden structures while searching for mates and favorable sites to construct their nests. A male carpenter bee may be “aggressive” when protecting its nesting site, but is harmless because it does not have a stinger. And although a female has a stinger, she will not usually sting unless handled or bothered.

Carpenter bees nest in wood; common nesting sites include house siding, eaves, window trim, fascia boards, decks, fences, and outdoor furniture.

Figure 3. Carpenter bee entrance hole. (Photo: Patty Alder, NCSU)

One sign of carpenter bee infestation is the nearly perfect round 1⁄2-inch entrance holes in exposed exterior wooden surfaces (Figure 3). Another sign of activity is the pile of coarse sawdust underneath freshly drilled holes. The sawdust is cast out while carpenter bees excavate tunnels. Yet another sign of infestation is the yellow or brown staining from voided fecal matter.

Carpenter bees can cause considerable structural damage from repeated colonization of the same area. Woodpeckers often peck through the wood surface of carpenter bees’ tunnels to prey on the larvae inside, thus causing even more damage.

Prevention & Control. Bare, unpainted, or weathered softwood is especially vulnerable to carpenter bee attack. To help prevent carpenter bee infestation, paint or varnish all wood surfaces. For the best results, apply two coats of a good exterior primer and follow up with at least one coat of finish. Painting is not practical for many wood surfaces, however, and wood stains provide little protection.

In some cases, standard window screening can be used to keep bees from getting to areas of unpainted surfaces or other places where it might be difficult to paint. Strips of metal window screening work best; don’t use the fabric or plastic type. The screening can then be wedged or stapled into areas the bees are infesting.

Figure 4. Carpenter bee holes may be sealed with caulk or wood putty. (Photo: Patty Alder, NCSU)

Spray or dust insecticide may be placed directly into the carpenter bees’ entrance holes or adjacent wood surface to reduce carpenter bee activity. These control efforts should be attempted in late afternoon or at night when the bees are inside the wood tunnels. Treated tunnels may be sealed with caulk or wood putty (Figure 4); however, do not plug the holes immediately. Bees should be able to pass freely through the nest entrance where they will contact the insecticide and distribute it inside the tunnels. Also, any new mature bees will emerge through the openings and contact the insecticide placed there. In the fall, the holes should be filled with caulk or wood putty.

Paper Wasps. Another insect you may begin receiving calls about (if you haven’t already!) is the paper wasp. We all know that these insects 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 spring approaches and 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 5. Use an aerosol insecticide to destroy a paper wasp nest (Photo: Patty Alder, NCSU).

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” (Figure 5).

Solitary Ground-Nesting Bees. There are several kinds of small hairy or metallic bees that dig into the soil to nest, often collectively referred to as digger bees. This is a diverse group that comes from different families and the term digger bee can include the andrenid bees, halictid bees, and colletid bees. These are solitary bees and native pollinators that are active early in the season.

Each female digs a cylindrical underground tunnel as a nest (as opposed to social bees such as honey bees where only the queen reproduces and maintains a colony with the help of sterile workers). The underground nest is provisioned with a mixture of nectar and pollen collected from nearby flowering plants. This serves as food for the bee’s offspring (larvae) that develop in the underground chamber and emerge as adults the following year.

Figure 6. Digger bee mounds. (Photo from Ornamental Entomology ListServe)

Digger bees usually emerge in May and are active for a relatively short period – about 6-8 weeks or so. The first sign of digger bees in lawns is often little mounds of soil with a hole nearby (see Figure 6). The ground bees will also be flying over this area.

Control. Ground bees like dry soils. Watering the soil when bees first become active may deter nesting. Ground bees also prefer to nest in dry areas where the grass is thin. If possible, correct the problems making the turf thin. Find ways to thicken the turf in these areas to reduce ground bee problems. In areas that will not grow grass, mulching the area can help as well.

Figure 7. Sand boxes and other play areas may be covered with a tarp to reduce bee activity. (Photo: Mike Waldvogel, NCSU)

If the bees are flying around and attempting to nest in sandboxes or other areas children play, another option is to temporarily cover the area with a tarp until the bees have moved on (see Figure 7).

If you feel a pesticide is warranted, watch during the day to see where the holes are located. Each hole (nest) may then be treated directly with a dust or spray insecticide. A dust insecticide may cling to the bee’s body better than a spray. Keep people and pets out of the area while it is being treated.