Arborists and Stinging Insects in the Landscape: a Potentially Painful Encounter by Rick W
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SEPTEMBER 2015 N O . 1 8 2 Arborists and Stinging Insects in the Landscape: A Potentially Painful Encounter By Rick W. Harper and As arborists and urban for- early part of the season Jody Gangloff-Kaufmann esters we are well familiar and much easier to spot with Integrated Pest Management (IPM) as a sustainable, in late summer when inclusive approach to managing pests that require inter- populations peak. To vention strategies. It is important to keep in mind that quickly detect a stinging the benefits from the stinging insect community are nu- insect nest, scout the merous and include pollination (30% of food crops and perimeter of a structure 90% of wild plants require the pollination services of by slowly walking along bees (1)) and predation. On occasion, however, stinging and observing insect ac- insects may necessitate an intervention – especially if Honeybee swarm tivity. Look at the roof- they are frequenting high-use areas like our community (Timothy Haley, USDA line and eaves of the parks, urban trees and landscapes. When we put into Forest Service, Bugwood.org) structure with the sky as context that conflicts with stinging insects accounted for a backdrop; scout the more than “79 fatalities per year” in the U.S., and com- foundation of buildings and base of trees for activity. Pay prised “28.2% of the total animal-related fatalities from particular attention to dense brush, compost piles, 1999 to 2007 (2),” it becomes evident that a sting may boards on the ground, railroad ties that may be used as indeed be a serious occurrence. landscaping borders and wooden post-and-rail fences. Yellowjackets (Vespula spp.; Dolichovespula spp.) and bum- The intended outcome of using IPM is the reduction of ble bees (Bombus spp.) tend to nest closer to the ground, risk. These risks include negative economic, environ- while honey bees (Apis mellifera mellifera), paper wasps mental and human health side effects such as ineffective (Polistes spp.) and baldfaced hornets (Dolichovespula macu- pest management, costly damage from lata) prefer to nest in higher locations. Yellowjacket and Up Ahead: pests, unintentional pesticide poison- honey bee activity will appear like traffic, with many fora- ings, and health risks from pests. Ex- Stinging gers coming and going along an invisible highway. Bumble posure to stinging insects present Insects 1-4 bee and paper wasp nests have less traffic, but foragers risks from insecticide exposures, risks Species will purposefully return to a single spot. It should also be related to stings (i.e. envenomation or noted that honey bees are the only social (colony- Spotlight 5 anaphylaxis), and risk of injury from a building) stinging insects in the Northeast that survive the Growing on fall. Arborists and urban foresters winter as a colony, complete with foragers that emerge Trees 6 should be keenly aware of stinging in the early spring in large numbers. All other social wasp Webcasts 7 insects, understand personal- and bees overwinter as single mated queens in areas with protective strategies, and take steps Tech 9 temperate winters. Grants 10 to make the landscape a safer working Gleanings 11 and living environment. Binoculars are an important tool, useful in scouting for wasp and bee activity before initiating an ascent. It is es- News 13 Inspection pecially important to Inspect tree holes and crotches for On the Stinging insect colonies may be diffi- Horizon 14 cult to find in the outdoors in the (Continued on page 2) P A G E 2 SEPTEMBER 2015 Arborists and Stinging Insects in the Landscape yellowjacket or honey bee activity. Baldfaced hornets and ous situation, especially when climbing or working on a aerial yellowjackets (Dolichovespula arenaria) construct ladder, as the immediate reaction for most people is to paper carton nests that hang from trees, structures, and suddenly take one or many steps backwards! On the shrubs. Search the tree canopy and on the upper sides of ground, this may be fine, however when working on a structures for the gray paper nests. Use a rake or other ladder or in a climbing saddle you must be prepared for long-handled tool to hit and shake dense shrubs from a sudden hazards like a chance encounter with a wasp’s distance to check for activity. Also note that certain nest. If a thorough inspection using binoculars has not flowering shrubs and trees may host bee and wasp popu- turned up any evidence of wasps in your aerial destina- lations foraging for nectar. For example, black locust tion, they may still lurk. If the thought of encountering (Robinia pseudoacacia), Scholar-tree (Styphnolobium japoni- wasps on a ladder makes you nervous, invest in a bee veil cum), Linden (Tilia spp.) and many Hollies (Ilex spp.) are for face and neck protection. They can be purchased for attractive to stinging insects when they are in bloom. $15-20 at any online beekeeping supply company, and worn over or under a safety helmet. You might also con- Personal Precautions sider carrying an aerosol can of wasp spray for personal In late summer, paper wasp, yellowjacket and baldfaced protection, just in case. Those with known allergies to hornet populations and activity peak as the colonies pro- wasp and bee stings should take special precautions and duce new queens that will overwinter. There is a strong avoid encounters with stinging insect colonies. Multiple demand for carbohydrates (i.e. sugars) by the colony, stings can overwhelm a person’s immune system even resulting in the greatest numbers of workers more ag- when epinephrine is applied. In severely allergic patients, gressively foraging for diminishing resources. This puts death may occur in as little as one hour. wasp foragers in frequent contact with people working in the landscape, especially when sweet foods are available. PHYSICAL CONTROLS FOR STINGING It is not uncommon, for example, to observe donuts and INSECTS other sweets being made available at late summer events If you are faced with mitigating stinging insect problems like fairs, workshops and community festivals. Yellow- on a client’s property, determine the type of wasp or jackets may regularly be observed discovering and forag- bee present and consider whether non-pesticidal man- ing on these sweet treats – the precursor to a potentially agement tools will work. painful oral encounter! When a tree crew breaks for Sanitation lunch, they should never leave food or soda cans unat- Bees typically feed on flower nectar and pollen and do tended. Yellowjackets tend to crawl inside soda cans not present a problem around food or garbage. Although leading to very painful, possibly life threatening stings in they may be present in the landscape, individual bees are the mouth or on the lips. Another minor concern for not aggressive. Wasps, especially yellowjackets and paper urban foresters and landscapers is wasps, are scavengers and will forage sweat bees (Family: Halictidae), on ripe and fallen tree fruits, at food which are small (1/4 inch), dark or service areas and in garbage contain- sometimes brightly colored bees. ers. Sanitation involves removing They are attracted to perspiration these food sources to reduce wasp on human skin and females (like all foraging in areas where people work stinging insects) can sting. The sting or spend time. Collect and remove is minor, but somewhat painful or fallen fruits, preferably early in the itchy. Stings most commonly happen morning. Cover garbage containers when a bee lands on perspiring skin and be sure trash and recycling bins (behind the knees, for example) and are rinsed. Garbage, especially food become squeezed against the body. Sweat bee (Scott Bauer USDA ARS, waste, should be bagged in good The sting may become more serious bugwood.org) quality sealable bags to prevent spills for sensitive individuals. and limit access of wasps to food. Of course, inspect and Unfortunately, an unsuspecting arborist or urban for- protect any food and drinks you consume in the field to ester will sometimes discover a hidden nest while on the avoid being stung. job, resulting in full-scale colony alarm. This is a danger- (Continued on page 3) THE CITIZEN FORESTER department of Conservation and Recreation SEPTEMBER 2015 P A G E 3 Arborists and Stinging Insects in the Landscape (Continued from page 2) Traps Wasp traps, which are available at hardware stores, can reduce the number of foraging wasps. These are useful when activity is high and the nest cannot be found or is located on adjacent property. Hang these traps approxi- mately 2m above – ground and away from human activ- ity. Refresh traps no less than weekly by dumping the contents, rinsing and refilling with soda or fruit juice. An empty soda bottle can also be transformed into a cheap DIY wasp trap that is used in the same manner as the store-bought version (see quick “how to” at: http:// www.wikihow.com/Make-a-Wasp-Trap). Cheap fruit punch and orange soda are very attractive baits. Place these traps away from human activity, preferably on top Baldfaced hornet nest (Rita Parkins, Bugwood.org ) of a shed or hanging at about 5-6 feet. Traps are not available, nor necessary, for bees. entrance on an A-frame ladder. Allow the vacuum to run until traffic is reduced to an occasional wasp. For a large Nest removal and exclusion colony of thousands of workers, this may take an hour. Paper wasps construct visible hanging umbrella nests on Seal the hose end of the vacuum and let it sit for a day in buildings, fences, under decks and in dense shrubs. Nests the sun, or seal the vacuum in a heavy-duty black plastic should be knocked down early in the season using a pole bag for 1-2 days.