Featured Creature: Horntails and Wood Wasps

The names “wood wasp” and “horntail” describe several kinds of wood-boring insects in the Order Hymenoptera, Family Siricidae. Of greatest concern are the large, non-stinging wasps that are attracted to and complete their life cycles in newly dead or dying conifer trees. If timber is salvaged from these trees, adult wasps may emerge from infested lumber in recently completed structures (see Figure 1). 

Figure 1. Wood sawn from a tree damaged by Sirex noctilio (Photo by Dennis Haugen, Bugwood.org).

There are several species of horntails, all looking very similar. They are large wasps, generally 1 inch or longer. They have a wasplike appearance but lack a noticeable constriction in the abdomen, as seen with many wasps. They are often black or metallic dark blue or combinations of black, red, and yellow.

 The male and female have a similar body shape, except the female is larger and has a very prominent ovipositor. The female can use her ovipositor only for egg laying; she can’t use it to sting in defense.

The female drills her ovipositor nearly 3/4” into the wood of a weakened or dying tree and lays 1 to 7 eggs.

She may lay up to 200 eggs in her lifetime. Eggs hatch in 3 to 4 weeks, and larvae tunnel into the wood parallel with the grain. Larval feeding continues through 5 or more immature stages, which take at least a year and as many as 5 years in cooler climates to complete. The tunnel, or gallery, usually measures 10 to 12 inches long at completion.

Pupation takes place at the end of the gallery. After 5 or 6 weeks as a pupa, the adult emerges by chewing through about 3/4” of wood, leaving a round exit hole 1/4” – 1/2” diameter.

Although they can be extremely annoying, and can look intimidating to many people, horntails are not harmful to humans or structures. They only attack trees and won’t bore into wood in buildings or furniture, and therefore, will not re-infest structures. Fortunately, the damage is more cosmetic and does not cause any real structural damage. The only real management strategy would be to repair or replace any cosmetic damage. 


Spring Cleaning to Prevent Pests

Most folks love spring! But with spring comes many pests – insects and others – that begin to emerge and become active in and around our homes. Fortunately, with spring also comes spring cleaning for many people. And with just a little extra time and energy, many pests can be kept at bay.

Ants, cockroaches, stored product pests, mice, and termites are just a few critters that may try to take up residence in and around our homes. Follow these cleaning and organizing tips for areas in and around the home to help maintain a pest-free environment.

Figure 1. Crumbs and other debris beneath appliances should be cleaned up (Patty Alder, NCSU).

Inside Cleaning As most of us know, the kitchen holds many items attractive to pests. Food, water, sources of heat, and harborage areas can be big draws for pests. Inevitably, food, crumbs, grease, and other debris collect under appliances over time (see Figure 1). Move the stove and refrigerator out from the wall and clean the floor beneath these items thoroughly. Go through the pantry and other places food is stored and get rid of old, expired items. Store any pest-susceptible items in sealable, pest-proof containers. Many susceptible items can be stored in the refrigerator as well. Remove items from cabinets and give the shelves a good wipe down before returning items. Lastly, don’t forget to finish by thoroughly cleaning countertops and giving the floor a good vacuuming and mopping. 

Ideally, the kitchen trash can should have a tight-fitting lid. In addition, you may consider placing your recyclables in a container with a lid – even rinsed recyclables can contain enough residue to attract pests. 

For both kitchens and bathrooms, check to make sure there are no leaky pipes or faucets. In addition, seal up any gaps around pipes with caulk or expandable foam. 

Figure 2. Cluttered storage areas, such as the garage should be cleaned and organized (Mike Waldvogel, NCSU).

Declutter closets, basements, garages, attics, or other storage areas pests may be hiding (see Figure 2). Donate or throw out unused or unnecessary items. The less stuff you having lying around, the fewer hiding places available for pests. If possible, use plastic storage tubs with tight-fitting lids to organize and store items in.

Exterior Cleaning Seal up entryways on the outside of your home. Gaps around pipes that enter the foundation can be caulked closed. 

Weatherproof doors and window frames. Make sure window and door screens fit properly and are not ripped or torn. Crawl space and attic vents should be screened to keep out unwanted pests.

Reduce or eliminate any outdoor clutter that could be serving as pest harborage. Store firewood, lumber, and other items away from the foundation. 

Trim back branches that are touching the structure. If possible, leave a 12” to 18” vegetation free zone around the foundation.

Eliminate mosquito breeding sites by clearing your yard of standing water. Anything that collects and holds water could be a potential problem. Areas/items that should be checked include:

  • Bird baths (make sure water is replaced every 2-3 days)
  • Clogged gutters
  • Drain pipes attached to downspouts
  • Buckets, watering cans, etc.
  • Saucers beneath potted plants
  • Tarps covering woodpiles or other items
  • Children’s toys, including plastic kiddy pools
  • Tires
  • Grill covers, boat covers, etc.
  • Garbage cans, recycle bins, etc.
  • Any trash or debris that can collect water

In summary, warmer weather means an increase in pest presence and activity. But with a little spring cleaning and home improvements, pests can be deterred from infesting your home and yard, making spring much more enjoyable!

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!