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Jwell-loved social feature of summers in Alaska isthe barbecue: human tastebuds are made happy withmeals in the outdoors. But those delicious grilled meats

attract not only the neighbors, but the wasps. The yellowjacket isas much a feature of summer outdoor cooking as the mosquito,and in recent years, has been quite plentiful in the Fairbanksarea, causing consternation and painful confrontations.

Alaskans are familiar with both the distinctive black-and-yellow-striped common yellowj ackets (Vespula vulgaris)and the nests of bald-faced hornets (Dolichovespula maculata)and aerial yellowjackets (Dolichovesp u/a arenaria), but maynot be familiar with their distinctive features. As Ned Rozell

Agroboreats. summer 2007

pointed out in his Alaska Science Forum column, commonyellowjackets are scavengers, nesting in ground cavities, with"a taste for garbage and good barbecues." Because peoplemay not realize the difference in nesting habits amongyellowjackets and hornets, they "often make the mistakeof destroying the gray, paper-mach-looking, tree-hangingnests of vulgaris' cousins, macuLata and arenaria, who preferinsects to unattended steak." Agricultural Research Servicescientists Landolt, Pantoja, Hagerty, Green, and Emmert havebeen studying social wasps in Alaska, because even thoughyellowjackets and their relatives are a fact of life in the North,not much is known about them.

A bald-faced hornet,Dolichovespula maculata,perched at the entrance toits hive. These wasps are thelargest in Alaska, and have ataste for sweets and insect prey.

-PHOTO BY HAT REED AND Rick-i ZACK

Wasps of AlaskaWasps of the subfamily Vespinae arecommonly referred to as yellowjacketsand hornets. in proper usage, theterm yellowjacket refers to all membersof the genus Vespula Thomson andDolichovespula Rohwer, whereas theterm hornet refers to members of the OldWorld genera Vespa L. However, manypeople refer to any species with an aerialnest as a hornet, and any species with anunderground nest as a yellowjacket. Thisgroup of social insects is of importanceto man as both beneficial predatorsof pest insects and as pestiferousscavengers. Miller, in a 1961 article,and Akre et al., in their 1980 handbook,Yellowjackets ofAmerica north ofMexico,report ten species of yellowjackets fromAlaska; Dolichovespula albida (=D.norwegica), D. arctica (Rohwer), D.arenaria, D. norwegicoides (Sladen), D.macuiata (L.), Vespula vulgaris (L.), Vacadica (Sladen), V austriaca (Panzer),V consobrina (Saussure), and V mufa L.(=intermedia (Buysson).

A technical bulletin on stinginginsect management published in 2002by the company IPM of Alaska lists

Agroocreas,

three species, Vespula maculifrons(Buysson), V squamosa (Saussure),and Dolichovespula maculata (as V.maculata) as common pests in Alaska.(However, the listing of V maculfionsand V squamosa as pests in Alaska wasin error, since both species are restrictedto the eastern United States and lowerlatitudes.)

Brian Barnes, et al., of the UAFInstitute of Arctic Biology, reported in1996 on the overwintering habits of Vvulgaris. There is little else known ofAlaska's wasp species.

The GoodYellowjackets and hornets serve asimportant predators of other insects.They are well known to prey oncaterpillars, grasshoppers, flies, andmyriad other types of insects of farm,garden, and forest. In this manner,they help keep populations of manyinsect species in check. They in turnare food for some birds and mammalsthat will eat them singly or dig up thenest to consume the larvae. Althoughnot a common benefit, there are alsoflower species, such as Trilliums, that arepollinated by visiting wasps.

Yellowjackets can be a pest in Alaska inareas inhabited by people and animals,in particular when they build their nestson or near human structures. ManyVespula and Dolichovespula speciespose stinging hazards to humans, pets,and farm animals. The two recentyellowj acket-related human fatalitiesin Fairbanks in summer 2006 clearlyillustrate the potential danger ofstings, particularly for those who areallergic to the yellowjacket's venom.Most unpleasant human-yellowjacketinteractions occur when the waspsare either defending their nests fromdisturbance or scavenging for food.

The Not-So-BadAll species of yellowjackets will

respond with aggression and defendtheir nest if the nest is disturbed;however, not all species exhibitscavenging behavior. Food-gatheringbehavior of yellowjackets varies widely.Members of the V mufa species group(V m-ufa, V acadica, and V consobrjnain Alaska) primarily are hunters oflive insect prey; V vulgaris wasps are

6Vespul.a vulgaris.

-PHOTO BY DEREK SyRES, UA MUSEUM OF THE NORTH

commonly scavengers and hunt insect prey;members of the genus Dolichovespula (D.arenaria, D. macu/san, and D. norvegicoides)fall somewhere in between. V austriaca andD. adulterine are social parasites in the nests ofother yellowjackets; a queen invades the nest ofanother yellowjacket species (D. arenaria, D.norvegicoides, V rufa, and V acadica) and relieson that nest's workers to raise her young.

Trapping the WaspsTo find out more about the local populationsof wasps, we used attractant-baited traps tocollect data on species composition, distribu-tion, and pest status of eight species of waspcaptured in Fairbanks, Delta Junction, andPalmer, Alaska, from May to September. Ourstudy was conducted during 2003 and 2004to assess the relative abundance and species di-versity of vespine wasps in Alaska agriculturalhabitats. Organic and low-chemical-inputfarms producing potatoes, rhubarb, and othervegetable crops near Fairbanks, Delta Junction,and Palmer were chosen as study sites.

The chemistry of attractants useful intrapping and monitoring yellowjacket waspshas been discussed by several authors (seereferences below); heptyl butyrate and aceticacid plus isobutanol have been reported asattractive to various yellowjacket species. In anarticle published in 2005 by Landolt, Pantoja,and Green in the Journal ofthe British ColumbiaEntomological Society we reported in detail onthe responses of Alaska wasps to chemicalattractants; we found that the different speciesof yellowjackets were attracted in varyingdegrees to different chemical attractants. Vacadica, V consobrina, and V rufa were attractedto heptyl butyrate; V vulgaris and D. maculatawere attracted to acetic acid plus isobutanol. Itappeared that D. arena na and D. norwegicoideswere poorly attracted to either lure.

YeIIowjacke I Spec. :ci AiasKaVespula vu!garis L.Known worldwide as the common wasp, vulgoris is an underground nester thatincreases in abundance from June into September. It is a serious pest because itcan be very abundant and is a scavenger of both meats and sweets. Because ithides its nest underground and will defend it vigorously, an unsuspecting personor animal can be in real trouble by stepping on or near the nest site.

V. acacijco (Saden)This species is similar in appearance to vulgaris, and is also an undergroundnester. However, it is far less abundant, peaks in numbers in early August, andoccurs in smaller colonies. It generally does not scavenge and is not a pestunless a nest is disturbed.

V. consobrina (Soussu.Consobrina is similar in biology to acadica, with small underground colonies,a short colony cycle, and small populations. It also does not scavenge and isnot routinely in contact with people. It is noteworthy in being white and black,rather than yellow and black.

V. ruin (L.) (—sriterrnedicThe name rufo refers to the red markings on the fore part of the abdomen of thiswasp, which is otherwise black and yellow. It also is not generally a pest, nestsunderground, and does not scavenge. It is most abundant in late July and earlyAugust.

V. ausrr....This species is a social parasite of ocadica and rufa. Only the queens and malesare encountered because there is no small female worker caste. Its principlesignificance is probably its suppression of populations of ocadica and rufa.

Dolichovespula maculata (L

The bald-faced hornet is noteworthy in several regards: it is the largest speciesof social wasp in Alaska, is strikingly white and black rather than yellow andblock, and makes aerially placed nests that are round or oval. Disturbance ofinterlocking shrub or tree branches can easily bring this insect to attack. It ismore often seen as a scavenger of sweets than meat.

D. arer'aria (FThis species is referred to as the aerial yellowjacket because it is the mostcommon yellow and black wasp to place nests above ground: in shrubs andtrees, or attached to eaves of buildings. Again, it is a stinging threat if the nestsite is disturbed. One must be alert walking through tall brush, because the nestis hard to see and a hiker can disturb the nest without even knowing it is there.Like maculata, it is more of a scavenger of sweets, and is generally not seen onyour ham sandwich.

D. norwegica (a/b,da [Sladen])This wasp is an aerial nester but is much less abundant than arenaria and isnot much of a pest threat. Many specimens have small red markings on theabdomen and are otherwise white and black.

D. adulterina (Buysso::)Adulterina, previously known as Dolichovespuia arctica, is a social parasite of D.arenaria. Only queens and males are seen, with no worker caste. It is white andblack, and looks similar to Vespula consobrino. It has no pest status. Rather, itmay reduce numbers of the more pestiferous aerial yellowjacket.

D. norve9 ico,des (SaoenThis species looks like a dark version of arenario. It also makes aerial nests, but isnot quite as common as arenaria.

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We captured the wasps using commercial traps (AgrisenseDome or Trappitt). The traps are pear-shaped with invertedfunnels beneath and with clear plastic tops and opaqueyellow bottoms, within which is placed a drowning solution(0.125% soap and 2% boric acid in water). Wasps enter thetrap from below through the inverted funnel and becometrapped in the drowning solution. Chemical attractants werehepty butyrate and acetic acid with isobutanol, dispensedfrom 15 ml polypropylene bottles with 6 mm holes in thelid for chemical release. Bottles were suspended inside thetrap from the top with wire. Traps were placed 20 m apart,at a height of 1.5 m on vegetation or on fences. We checkedthe traps weekly, replacing the drowning solution each week.The chemical lures were replaced every thirty days. Insectswere identified by descriptions, illustrations, and keys inMiller's 1961 article, in the USDA handbook Yellowjacketsof America north of Mexico, and following the taxonomy ofCarpenter and Kojima. From these captured wasps we tookvoucher specimens for deposit in the James EntomologicalCollection at Washington State University in Pullman andwith the USDA ARS Subarctic Agricultural Research Unit inFairbanks. (A voucher specimen is any specimen that serves asa basis of study and is retained as a reference.)

\.I,s VLligJfl S. 01 (lSS012 yollou,zcker, co;izoJr a landing (Center) to its underground nest.

Below: nest and workers ofDolichovespula maculata, the bald-facedhornet, under the eave ofa building.

—PHOTOS BY HAL REED AND RICH ZACK

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Genus/SpeciesFairbanksDeltaJunction

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D. norvegicoidesx x

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V. acadica x x

V. consobrina x x

x = indicate presence of that species in locality= indicates reported from Alaska, but not collected during

this studyn = not collected from this localityF = social parasitesB = beneficialS = scavenger/potentially pestiferous

The lures:heptyl butyrateThis synthetic chemical has a fruity odor and isstructurally similar to natural fruit esters,iso b u a noThis chemical is produced naturally duringthe fermentation of carbohydrates. It mayalso be a byproduct of the decay process oforganic matter,acetic coThis corrosive chemical is found in vinegar andother substances, and is best recognized forits sour (vinegary) taste and pungent smell.

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Pestiferous Populations?Ten species of yellowjackets were collected: Vespulavulgaris L., V acadica (Sladen), V consobrina (Saussure),V rufa (L.) (=intermedia [Buysson]), V austriaca(Panzer), Dolichovespula maculata (L.), D. arenaria(F.), D. norwegica (=albida [Sladen]), D. adulterina(Buysson), and D. norvegicoides (Sladen).

The common yellowjacket, V vulgaris, was themost abundantly trapped species during both years andat all three study locations (see table and figure). Queenswere captured in late May and early June; workers werecaptured between mid-June and early October, andmales were captured from late July into late September.Most of the samples consisted of workers that wereabundantly trapped from mid-July into late August.

Vespula acadica queens were captured in lateJune and again in mid-September. Workers werecaptured from mid-June to mid-September. WorkerV consobrina were captured in traps from early Julyto August in Delta Junction and from June to Julyin Fairbanks. Workers of V rufa were captured fromJune to July in Delta Junction, from June to Julyin Fairbanks, and August in Palmer. Few Vespulaaustriaca, D. adulterina, D. arenaria, D. norwegicoides,or D. norwegica wasps were captured in this study.

Although Miller and Akre report that V. consobrinais absent from most of Alaska, this species was capturedat Fairbanks and Delta Junction, and although theyindicate the presence of Dolichovespula alpicoia wasps,none were collected during our study. Their absencefrom trap catches could have been the result of theirabsence from the study area, low population density, ora lack of response to the chemical attractants.

The seasonal pattern of wasp captures in trapsindicates a broad period of activity—early July to earlySeptember—during which they could be pestiferous.

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Figure 1. Population dynamics ofyellowjackets in three localities ofAlaska.Sites are Fairbanks (open triangle), Delta Junction (filled square), andPalmer (open circle).

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.1 aA close view of the common western yellowjacket, Vespula vulgaris.

-PH01 0 c I-lu Rcco AND RICH ZAcI<

Due to its abundance and the scavenging behavior that bringsit into frequent contact with people, V vulgaris is consideredof particular importance. The bald-faced hornet D. maculatamay also be pestiferous in Alaska due to its abundance duringJuly and August. Other species of wasps captured, such asV acadica, and V consobrina, are less likely to be pestiferousbecause they are not known for scavenging habits, occur insmaller colonies, and do not occur in high densities, comparedto species such as V vulgaris.

-.cknowledgementsTechnical support was provided by T. Adams, L. DeFoliart, D.Hall, K. Maher, J . Malapanis, and R. Torgerson in Alaska and byJ . MacKenzie in Yakima, Washington. This work was supported inpart by a Cooperative Research and Development Agreement withSterling International, Inc. of Spokane, Washington.

References & FurtherAkre, RD., A. Greene, J.F. MacDonald, P.J. Landolt, and H.G.Davis. 1980. Yellowjackets of America north of Mexico. USDAHandbook 552.

Barnes, B.M., J.L. Barger, J . Seares, P.C. Tacquard, and G.L.Zuercher. 1996. Over-wintering in yellowjacket queens (Vespulavulgaris) and green stinkbugs (Elasmostethus interstinctus) in subarcticAlaska. Physiol. Zool. 69: 1469-1480. Available on line at http://mercury.bio.uaf.edu/ .-brian_barnes/publications/ 1 996barnes_etal.pdf (accessed May 2007).

Carpenter, J.M. and J . Kojima. 1997. Checklist of the species in thesubfamily Vespinae (Insecta: Hymenopetra: Vespidae). Nat. HistoryBulletin Ibaraki University 1: 51-92.

Davis, HG., G.W. Eddy, TB McGovern, and M. Beroza. 1969.Heptyl butyrate, a new synthetic attractant for yellowjackets. IEcon. Entomol. 62: 1245.

Davis, HG., R. W. Zwick, W.M. Rogoff, TB McGovern, andM. Beroza. 1973. Perimeter traps baited with synthetic lures forsuppression of yellowjackets in fruit orchards. Environ. Entomol.2: 569-571.

Fricdcnauer, M. and R. Duffy. 2006. Yellowjacket sting suspectedin man's death. Fairbanks Daily News-Miner. htip://www.news-miner.com/Stories/0,1413,113-7244-3346072,00 . html# (July 10edition, accessed 2006).

Greene, A. and D.M. Caron. 1980. Entomological Etymology:The common names of social wasps. Ann. Entomol. Soc. Amer.26:126-130.

Grothaus, RH., H.G. Davis, W.M. Rogoff, J.A. Fluno, and J.M.Hirst. 1973. Baits and attractants for east coast yellowjackets,Vespula spp. Environ. Entomol. 2: 717-718,

Howell, JO., TB McGovern, and M. Beroza. 1974. Attractivenessof synthetic compounds to some eastern Vespula species. f Econ.Entomol. 67: 629-630.

IPM. 2002. Stinging Insect Management; THE PROBLEM:Yellowjackets and Hornets. Available on line at http://www.ipmofalaska.com/files/ycllowjackets.html (accessed May 2007).

Kincaid, T. 1900. Papers from the Harriman Alaska Expedition. xiv.Entomological Results (8): The Sphegoidea and Vespoidea of theExpedition. Proc. Wash.Acad. ofSci. 11: 109-112.

Landolt, P.J. 1998. Chemical attractants for trapping yellowjacketsVespula germanica (Fab.) and Vespula pensylvanica (Saussure)(Hymenoptera: Vespidae). Environ. Entomol. 27: 1229-1234.

Landolt, P.J. 1999. A chemical attractant for the golden paper wasp,Polistes aurifir Saussure (Hymenoptera: Vespidae). I Kan. Entomol.Soc. 71: 69-73.

Landolt, P.J., H.C. Reed, JR. Aldrich, A.L. Antonelli, and C.Dickey. 1999. Social wasps (Hymenoptera: Vespidae) trapped withacetic acid and isobutanol. Florida Entomol. 82: 609-614.

Landolt, P.J., H.C. Reed, and D.J. Ellis. 2003. Trapping yellowjackets(Hymenoptera: Vespidae) with heptyl butyrate emitted fromcontrolled release dispensers. Florida Entomol. 86: 323-328.

Landolt, P., A. Pantoja, and D. Green. 2005. Yellowjacket wasps(Hymenoptera: Vespidae) trapped in Alaska with heptyl butyrate,acetic acid and isobutanol. f Entomol. Soc. British Columbia. 102:35-41.

MacDonald, J.F., R.D. Akre, and W.B. Hill. 1973. Attraction ofyellowjackets ( Vespula spp.) to heptyl butyrate in Washington state(Hymenoptera: Vespidae). Environ. Entomol. 2: 375-379.

Miller, CD. F. 1961. Taxonomy and distribution of nearctic Vespula.Can. Entomol. Suppl. 22. 52 pp.

Mowry, Tim. Wasp sting blamed for second death in Fairbanks.Fairbanks Daily News-Miner, August 26, 2006. Available on line athttp://newsminer.com/2006/08/26/1716 (accessed 5/1/07)

Reed, H.C. and P.J. Landolt. 2002. Trap response of Michigansocial wasps (Hymenoptera: Vespidae) to the feeding attractantsacetic acid, isobutanol, and heptyl butyrate. Great Lakes Entomol.35: 71-77.

Rozell, Ned. Warm Spring Helps Yellow Jackets Crash the Party.Alaska Science Forum #1232. April 27, 1995. Available on line athttp://www.gi.alaska.edu/ScienceForum/ASF12/1232.html

Shippey, S. 1994. Minimize pest problems with yellowjackets.Fairbanks Daily News-Miner (July 17), page H6.

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queen (left) and workers on nursery combs.Left: Hornet nest (D. maculata) on birch tree.

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