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!

 

 

Eastern Equine Encephalitis

 

Adult asian tiger mosquito resting on foliage

Asian tiger mosquito (photo – Susan Ellis (www.bugwood.org)

Late Friday  (10/13), the Jacksonville Daily News reported that a pony had died of what is suspected to be Eastern Equine Encephalitis (EEE) which is transmitted by mosquitoes.  In 2016, there was one reported veterinary case of EEE and that was in Pitt County.  In 2015, there were five veterinary cases including one in Onslow County.  Human cases of EEE are uncommon.  According to the CDC  n the ten year period (2007-2016), North Carolina had eight human cases of the disease.

It’s important to understand that the virus is not transmitted from one horse to another (or from a horse to a human) or from one person to another.  Also, mosquitoes acquire the virus from feeding on infected birds primarily down in the hardwood swamp areas in the southeastern part of our state (where fewer people live).  This unfortunate incident doesn’t mean that people need to run out and treat their property with pesticides. It does serve as a reminder that, even though temperatures are starting to drop, it’s still a good idea to use personal protection when engaging in work or recreational activities outdoors.  Also, while we’re outdoors cleaning up fallen leaves and pine needles and/or planting flowers or shrubs for next spring, it’s a good idea to look around at areas that are or could be mosquito breeding grounds and eliminate them.  More information about mosquito control can be found here:  https://entomology.ces.ncsu.edu/mosquito-control-around-homes-and-in-communities/

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.