Influence of elevation on bark beetle (Coleoptera: Curculionidae, Scolytinae) community structure and flight periodicity in ponderosa pine forests of Arizona

We examined abundance and flight periodicity of five Ips and six Dendroctonus species (Coleoptera: Curculionidae, Scolytinae) among three different elevation bands in ponderosa pine (Pinus ponderosa Douglas ex. Lawson) forests of northcentral Arizona. Bark beetle populations were monitored at 10 sites in each of three elevation bands (low: 1,600-1,736 m; middle: 2,058-2,230 m; high: 2,505-2,651 m) for 3 yr (2004-2006) using pheromone-baited Lindgren funnel traps. Trap contents were collected weekly from March to December. We also studied temperature differences among the elevation bands and what role this may play in beetle flight behavior. Bark beetles, regardless of species, showed no consistent elevational trend in abundance among the three bands. The higher abundances of Ips lecontei Swaine, I. calligraphus ponderosae Swaine, Dendroctonus frontalis Zimmerman, and D. brevicomis LeConte at low and middle elevations offset the greater abundance of I. knausi Swaine, D. adjunctus Blandford, D. approximatus Dietz, and D. valens LeConte at high elevations. I. pini (Say) and I. latidens LeConte were found in similar numbers across the three bands. Flight periodicity of several species varied among elevation bands. In general, the flight period shortened as elevation increased; flight initiated later and terminated earlier in the year. The timing, number, and magnitude of peaks in flight activity also varied among the elevation bands. These results suggest that abundance and flight seasonality of several bark beetles are related to elevation and the associated temperature differences. The implications of these results are discussed in relation to bark beetle management and population dynamics.     

Evaluation of funnel traps for characterizing the bark beetle (Coleoptera: Scolytidae) communities in ponderosa pine forests of north-central Arizona

Lindgren funnel traps baited with aggregation pheromones are widely used to monitor and manage populations of economically important bark beetles (Coleoptera: Scolytidae). This study was designed to advance our understanding of how funnel trap catches assess bark beetle communities and relative abundance of individual species. In the second year (2005) of a 3-yr study of the bark beetle community structure in north-central Arizona pine (Pinus spp.) forests, we collected data on stand structure, site conditions, and local bark beetle-induced tree mortality at each trap site. We also collected samples of bark from infested (brood) trees near trap sites to identify and determine the population density of bark beetles that were attacking ponderosa pine, Pinus ponderosa Douglas ex Lawson, in the area surrounding the traps. Multiple regression models indicated that the number of Dendroctonus and Ips beetles captured in 2005 was inversely related to elevation of the trap site, and positively associated with the amount of ponderosa pine in the stand surrounding the site. Traps located closer to brood trees also captured more beetles. The relationship between trap catches and host tree mortality was weak and inconsistent in forest stands surrounding the funnel traps, suggesting that trap catches do not provide a good estimate of local beetle-induced tree mortality. However, pheromone-baited funnel trap data and data from gallery identification in bark samples produced statistically similar relative abundance profiles for the five species of bark beetles that we examined, indicating that funnel trap data provided a good assessment of species presence and relative abundance.     

Importance of resin ducts in reducing ponderosa pine mortality from bark beetle attack

The relative importance of growth and defense to tree mortality during drought and bark beetle attacks is poorly understood. We addressed this issue by comparing growth and defense characteristics between 25 pairs of ponderosa pine (Pinus ponderosa) trees that survived and trees that died from drought-associated bark beetle attacks in forests of northern Arizona, USA. The three major findings of our research were: (1) xylem resin ducts in live trees were >10% larger (diameter), >25% denser (no. of resin ducts mm⁻²), and composed >50% more area per unit ring growth than dead trees; (2) measures of defense, such as resin duct production (no. of resin ducts year⁻¹) and the proportion of xylem ring area to resin ducts, not growth, were the best model parameters of ponderosa pine mortality; and (3) most correlations between annual variation in growth and resin duct characteristics were positive suggesting that conditions conducive to growth also increase resin duct production. Our results suggest that trees that survive drought and subsequent bark beetle attacks invest more carbon in resin defense than trees that die, and that carbon allocation to resin ducts is a more important determinant of tree mortality than allocation to radial growth.     

Mountain pine beetle attack associated with low levels of 4-allylanisole in ponderosa pine

Mountain pine beetle (Dendroctonus ponderosae) is the most important insect pest in southern Rocky Mountain ponderosa pine (Pinus ponderosa) forests. Tree mortality is hastened by the various fungal pathogens that are symbiotic with the beetles. The phenylpropanoid 4-allylanisole is an antifungal and semiochemical for some pine beetle species. We analyzed 4-allylanisole and monoterpene profiles in the xylem oleoresin from a total of 107 trees at six sites from two chemotypes of ponderosa pine found in Colorado and New Mexico using gas chromatography-mass spectroscopy (GC-MS). Although monoterpene profiles were essentially the same in attacked and nonattacked trees, significantly lower levels of 4-allylanisole were found in attacked trees compared with trees that showed no evidence of attack for both chemotypes.     

Components of tree resilience: effects of successive low‐growth episodes in old ponderosa pine forests

Recent world‐wide episodes of tree dieback have been attributed to increasing temperatures and associated drought. Because these events are likely to become more common, improved knowledge of their cumulative effects on resilience and the ability to recover pre‐disturbance conditions is important for forest management. Here we propose several indices to examine components of individual tree resilience based on tree ring growth: resistance (inverse of growth reduction during the episode), recovery (growth increase relative to the minimum growth during the episode), resilience (capacity to reach pre‐episode growth levels) and relative resilience (resilience weighted by the damage incurred during the episode). Based on tree ring analyses, we analyzed historical patterns of tree resilience to successive drought‐induced low growth periods in ponderosa pine trees growing in unmanaged, remote forests of the Rocky Mountains. Low‐growth periods registered in tree rings were related to anomalies in the Palmer drought severity index (PDSI) and were attributed to drought. Independently of the impact of a specific event, subsequent growth after a single low‐growth episode was related to the growth prior to the event. Growth performance differed with tree age: young trees were overall more resistant to low‐growth periods, but older trees recovered better from more recent events. Regardless of tree age, recently burned sites exhibited lower post‐episode growth and lower resistance and resilience than unburned ones. We found mixed evidence for the cumulative effect of past low‐growth episodes: overall, greater impacts of a prior event and greater cumulative effects of past low‐growth periods caused a decrease in resistance. However, we did not find a progressive decrease in resilience over time in old trees. Our results highlight the value of using a combination of estimators to evaluate the different components of resilience. Specifically, while tree responses to disturbance depend on past disturbance episodes, the response is context‐specific and depends on the impact the capacity to recover after disturbance. This suggests that recent increases in forest mortality under current climate trends could relate to thresholds on specific components of resilience (resistance, recovery, resilience itself) rather than to an overall loss of resilience over time. Identifying such thresholds and their underlying mechanisms is a promising area of research with important implications for forest management.     

Charcoal and shrubs modify soil processes in ponderosa pine forests of western Montana

In split-root systems of alfalfa (Medicago sativa L.), already existing nodules or arbuscular mycorrhizal roots suppress further establishment of symbiosis in other root parts, a phenomenon named autoregulation. Roots treated with rhizobial nodulation signals (Nod factors) induce a similar systemic suppression of symbiosis.In order to test the hypothesis that flavonoids play a role in this systemic suppression, split-root systems of alfalfa plants were inoculated on one side of the split-root system with Sinorhizobium meliloti or Glomus mosseae or were treated with Nod factor. HPLC-analysis of alfalfa root extracts from both sides of the split-root system revealed a persistent local and systemic accumulation pattern of some flavonoids associated with the different treatments. The two flavonoids, formononetin and ononin, could be identified to be similarily altered after rhizobial or mycorrhizal inoculation or when treated with Nod factor.Exogenous application of formononetin and ononin partially restored nodulation and mycorrhization pointing towards the involvement of these two secondary compounds in the autoregulation of both symbioses.     

Attraction of the bark beetle Tomicus piniperda to Scots pine trees in relation to tree vigor and attack density

The attraction of Tomicus piniperda (L.) (Coleoptera: Scolytidae) to Scots pine trees of low and higher vigor with and without previous attacks was monitored with sticky traps. Somewhat higher numbers of beetles were caught on low vigor trees than on trees of higher vigor, indicating differences in olfactory stimuly between the two classes of trees.Many more beetles were caught on trees attacked by T. piniperda and on trees with simulated bark beetle galleries (manually drilled holes) than on control trees with no or only a few attacks. The strong attraction of beetles to attacked trees is attributed to the beetles responding to host volatiles released from the galleries.

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Zusammenfassung Der Anflug von Tomicus piniperda (L.) (Coleoptera: Scolytidae) an Kiefern in schlechtem oder besserem Gesundheitszustand, mit oder ohne vorherigen Befall, wurde mit Hilfe von Leimfallen untersucht. An Bäumen in schlechtem Zustand wurden etwas mehr Käfer gefangen als an Bäumen in besserem Gesundheitszustand. Das deutet auf Unterschiede in Geruchsreizen zwischen den beiden Klassen des Baumzustands hin.An Kiefern, die von T. piniperda befallen waren oder simulierte Einbohrungen (von Hand gebohrte Löcher) hatten, wurden viel mehr Käfer gefangen als an Kontrollbäumen ohne oder mit sehr geringem Befall. Der starke Anflug von Käfern an befallene Bäume wird gedeutet als Reaktion auf Duftstoffe des Wirts, die aus den Borkenkäfergängen abgegeben werden.

     

Response of understory vegetation to variable tree mortality following a mountain pine beetle epidemic in lodgepole pine stands in northern Utah

We analyzed the long-term dynamics of aboveground biomass ofLeymus chinense steppe in relation to interannual variation of precipitation and temperature during 1980–1989 at levels of community, growth form and species in the Xilin river basin, Inner Mongolia Autonomous Region, China. Annual aboveground net primary production (ANPP) varied from 154.00 g m^-2 yr^-1 in 1980 to 318.59 g m^-2 yr^-1 in 1988, with a mean of 248.63 g m^-2 yr^-1 and the coefficient of variation of 25%. ANPP was not significantly correlated to annual precipitation and total precipitation during April–September atp0.05 level, but precipitation in May and August accounted for 69% of interannual variation of ANPP. The means of rain use efficiency and water use efficiency ofL. chinense steppe were 8.1 kg DM ha^-1 mm^-1 yr^-1 and 0.89 mg DM g^-1 H₂O respectively. Aboveground biomass of various growth forms and species had different response patterns to interannual variation of precipitation and temperature. Monthly and seasonal distribution of precipitation and temperature were the key controls of aboveground biomass of species.     

Importance of log size on host selection and reproductive success of Ips pini (Coleoptera: Scolytidae) in ponderosa pine slash of northern Arizona and western Montana

Pine engraver, Ips pini (Say), often use thinning slash, and their populations are known to be influenced by the condition of this material. In our study, we evaluated the importance of three log diameters (5, 10, and 20 cm) and three lengths (60,120, and 240 cm) on various parameters of bark beetle host attack, development, and emergence. Evaluation of slash colonization in northern Arizona (near Flagstaff) and western Montana (near Missoula) over several years, during both spring and summer reproductive periods, indicated that the size of material selected by pine engraver differed by state, year, and season. However, within individual trials and over all trials, a trend in preference for larger diameter logs was apparent, whereas log length was of little effect. When evaluating only attacked logs, results indicated that the apparent preference for larger logs was not followed by significantly greater reproductive performance in the larger log sizes. Log origin was tested as a potential factor for the difference in attack densities between Arizona and Montana trials. Although male beetles in Montana and female beetles in Arizona seemed to distinguish between local-source and foreign-source logs during the attack phase, the gallery development and reproductive success of egg, larval, and new adult stages were not significantly different. Ultimately, differences among the trials both in host size selection and in reproductive success within attacked logs were closely tied to the overall population density of adult beetles. The implications of these findings for resource managers are discussed.     

Effects of mountain pine beetle on fuels and expected fire behavior in lodgepole pine forests, Colorado, USA

In Colorado and southern Wyoming, mountain pine beetle (MPB) has affected over 1.6 million ha of predominantly lodgepole pine forests, raising concerns about effects of MPB-caused mortality on subsequent wildfire risk and behavior. Using empirical data we modeled potential fire behavior across a gradient of wind speeds and moisture scenarios in Green stands compared three stages since MPB attack (Red [1-3 yrs], Grey [4-10 yrs], and Old-MPB [～30 yrs]). MPB killed 50% of the trees and 70% of the basal area in Red and Grey stages. Across moisture scenarios, canopy fuel moisture was one-third lower in Red and Grey stages compared to the Green stage, making active crown fire possible at lower wind speeds and less extreme moisture conditions. More-open canopies and high loads of large surface fuels due to treefall in Grey and Old-MPB stages significantly increased surface fireline intensities, facilitating active crown fire at lower wind speeds (>30-55 km/hr) across all moisture scenarios. Not accounting for low foliar moistures in Red and Grey stages, and large surface fuels in Grey and Old-MPB stages, underestimates the occurrence of active crown fire. Under extreme burning conditions, minimum wind speeds for active crown fire were 25-35 km/hr lower for Red, Grey and Old-MPB stands compared to Green. However, if transition to crown fire occurs (outside the stand, or within the stand via ladder fuels or wind gusts >65 km/hr), active crown fire would be sustained at similar wind speeds, suggesting observed fire behavior may not be qualitatively different among MPB stages under extreme burning conditions. Overall, the risk (probability) of active crown fire appears elevated in MPB-affected stands, but the predominant fire hazard (crown fire) is similar across MPB stages and is characteristic of lodgepole pine forests where extremely dry, gusty weather conditions are key factors in determining fire behavior.     

Effect of trap type, trap position, time of year, and beetle density on captures of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

The exotic redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), and its fungal symbiont Raffaellea lauricola Harrington, Fraedrich, and Aghayeva are responsible for widespread redbay, Persea borbonia (L.) Spreng., mortality in the southern United States. Effective traps and lures are needed to monitor spread of the beetle and for early detection at ports-of-entry, so we conducted a series of experiments to find the best trap design, color, lure, and trap position for detection of X. glabratus. The best trap and lure combination was then tested at seven sites varying in beetle abundance and at one site throughout the year to see how season and beetle population affected performance. Manuka oil proved to be the most effective lure tested, particularly when considering cost and availability. Traps baited with manuka oil lures releasing 5 mg/d caught as many beetles as those baited with lures releasing 200 mg/d. Distributing manuka oil lures from the top to the bottom of eight-unit funnel traps resulted in similar numbers of X. glabratus as a single lure in the middle. Trap color had little effect on captures in sticky traps or cross-vane traps. Funnel traps caught twice as many beetles as cross-vane traps and three times as many as sticky traps but mean catch per trap was not significantly different. When comparing height, traps 1.5 m above the ground captured 85% of the beetles collected but a few were caught at each height up to 15 m. Funnel trap captures exhibited a strong linear relationship (r2 = 0.79) with X. glabratus attack density and they performed well throughout the year. Catching beetles at low densities is important to port of entry monitoring programs where early detection of infestations is essential. Our trials show that multiple funnel traps baited with a single manuka oil lure were effective for capturing X. glabratus even when no infested trees were visible in the area.     

Synergistic effects of α-pinene and exo-brevicomin on pine bark beetles and associated insects in Arizona

The southern pine beetle (Dendroctonus frontalis) and western pine beetle (Dendroctonus brevicomis) cause significant mortality to pines in the southern and western United States. The effectiveness of commercial lures at capturing these bark beetles in Arizona has not been tested and may vary from other regions of their distribution. We conducted experiments using baited Lindgren funnel traps to investigate (i) if D. frontalis is more attracted to the standard commercial lure for D. brevicomis (frontalin + exo‐brevicomin + myrcene) than the D. frontalis lure (frontalin + terpene blend), (ii) whether replacement of myrcene with α‐pinene changes trap catches of Dendroctonus and associated insects, and (iii) whether the attraction to these lures varies across the geographical range of ponderosa pine forests throughout Arizona. In 2005, we tested various combinations of frontalin, exo‐brevicomin, myrcene and α‐pinene to D. frontalis, D. brevicomis and associated species. Dendroctonus frontalis, D. brevicomis and the predator Temnochila chlorodia were most attracted to lures with exo‐brevicomin. The replacement of the myrcene component with α‐pinene in the D. brevicomis lure resulted in the capture of twice as many bark beetles and Elacatis beetles. However, T. chlorodia did not differentiate between monoterpenes. In 2006, traps were set up in 11 locations around Arizona to test the relative attraction of lure combinations. In 9 out 11 locations, the D. brevicomis lure with α‐pinene was more attractive than the lure with myrcene or a terpene blend. These results suggest that the D. brevicomis lure with α‐pinene rather than myrcene is more effective lure to capture D. brevicomis and D. frontalis in Arizona. However, geographical variation in attractiveness to lures is evident even within this region of the beetles’ distributions. Differential attraction of Dendroctonus and their predators to these lures suggests potential use in field trapping and control programmes.     

The statistical and biological implications of sampling units for mountain pine beetle populations in lodgepole pine

Summary Populations of the mountain pine beetle in lodgepole pine were measured using two sample sizes: a single gallery—this is the basic family unit constructed by the parent beetles; and a 6- by 6-inch square area—the bark was removed and the brood counted. Data from the 6- by 6-inch sample were recorded in three ways. Each measurement unit provided different biological information and required different statistical considerations. The single gallery sample provided the most representative data of the entire population, but required additional biological measurement of attack density. The 6- by 6-inch sample brood data taken on an attack density basis provided the most statistically reliable information and encompassed the pertinent biological information. Percent survival, as could be used in elementary life tables, was rather consistent in all measurement units, regardless of point in time of sampling.     

Frequencies of null alleles at enzyme Loci in natural populations of ponderosa and red pine

Pinus ponderosa and P. resinosa population samples have mean frequencies of enzymatically inactive alleles of 0.0031 and 0.0028 at 29 and 27 enzyme loci, respectively. Such alleles are rare and are apparently maintained by selection-mutation balance. Ponderosa pine have much higher amounts of allozymic and polygenic phenotypic variation than red pine, yet both species have similar frequencies of null alleles. Thus, null alleles apparently do not contribute to polygenic variation, as has been suggested. The concordance between allozymic and polygenic variation adds support to the view that allozyme studies may be valuable in predicting the relative amount of polygenic variation in populations.     

Comparison of the initial demographies of pine and oak populations in rural pine forests in Korea and Japan

In order to understand the human impact upon demographic change in plant population in rural forests, we examined the population trends ofPinus densiflora andQuercus serrata inP. densiflora forests viewing their seedlings and saplings in rural Korea and Japan. The most prominent factor affecting the regeneration of the pine and oak was the intensity of management activity which controlled the vegetation stratification and its light environment. Open spaces, such as graveyard or cleaned area that allow the long-term direct daylight in dry season to accelerate the surface heat of soil, were unfavorable habitats for germination and growth of both species. The negative effects of the presence of litter and evergreen trees were related to the failure of early seedling and sapling growth of pine. Cover of litter is, especially, another factor related to the growth of pine saplings. It is considered that successful germination and sapling growth of pine and oak in early successional stages is determined by vegetation structures and light condition.     

Short-term development of ambrosia and bark beetle assemblages following a windstorm in French broadleaved temperate forests

Abstract: In most temperate deciduous forests, windstorm is the main source of dead wood. However, the effects of this natural disturbance on ambrosia and bark beetle communities are poorly known. In managed oak‐hornbeam forests storm‐damaged in France in 1999, we sampled ambrosia (and second bark beetles) by ethanol‐baited window‐flight traps in 2001. By comparing uncleared gaps, undisturbed closed‐canopy controls and seedling‐sapling stands, we investigated the short‐term effects of gap formation, gap size and surrounding landscape to provide a snapshot of scolytid response. Contrary to expectations, neither the abundance nor the richness of ambrosia beetle species was significantly higher in gaps than in undisturbed stands. Few responses in abundance at the species level and only a slight difference in assemblage composition were detected between gaps and closed‐canopy controls. Gaps were more dissimilar from seedling‐sapling stands, than from closed‐canopy controls. More scolytid individuals and species were caught in gaps than in seedling‐sapling stands. Mean local and cumulative richness peaked in mid‐size gaps. Only mid‐size gaps differed from closed‐canopy controls in terms of species composition. We identified generalist gap species (Xyleborus saxesenii, X. cryptographus), but also species significantly more abundant in mid‐size gaps (Platypus cylindrus, Xyloterus signatus). The faunistic peculiarity of mid‐size gaps seemed to be partly related to a bias in oak density among gap size classes. Few landscape effects were observed. Only the scolytids on the whole and X. dispar were slightly favoured by an increasing density in fellings at the 78 ha scale. We did not find any correlation between scolytid abundance and the surrounding closed‐forest percentage area. We confirmed that temperate, deciduous, managed stands did not come under threat by ambrosia and bark beetle pests after the 1999 windstorm. Nonetheless, our data stressed the current expansion in Western Europe of two invasive species, X. peregrinus and especially X. germanus, now the predominant scolytid in the three oak forests studied.     

Impacts of forest gaps on soil properties and processes in old growth northern hardwood-hemlock forests

We examined the influence of treefall gaps on soil properties and processes in old growth northern hardwood-hemlock forests in the upper Great Lakes region, USA. We found significantly greater solar radiation, soil moisture contents and soil temperatures in gaps compared to adjacent closed canopy plots. Gaps had significantly less exchangeable base cations (K, Ca, and Mg) compared to forest plots in the upper mineral soil (0–25 cm). Gaps also had significantly more dissolved organic N and extractable nitrate at depth (25–50 cm), indicating increased nutrient leaching in gaps. In-situ N mineralization was significantly greater in gaps and edge plots compared to forest plots. We found significantly greater potential N mineralization (measured in the laboratory at 25°C and 40% water holding capacity) in forest compared to gap plots. Microbial biomass N was significantly greater (ca. two-fold) in the gap edge compared to both gaps and closed forest. Using principal component analyses we found that edge plots were positively correlated with all principal components, indicating increased in-situ and potential N mineralization, microbial biomass N, soil NO₃⁻ and NH₄⁺, and soil organic matter. The gap edge may be a region of optimal microclimate and substrate to enhance microbial biomass and activity within these forest ecosystems. Responsible Editor: Bernard Nicolardet     

Patterns of cerambycid beetle species composition in relation to geographic features,climate and/or silvicultural treatments on different scales

Characterising geographic patterns of biodiversity generated by intrinsic distributions of organisms is essential for designing effective biodiversity conservation plans on both the project and sub-national to national scales. Species composition is generally similar within the same types of ecosystems located close to one another, but similarity also depends on the focal organism(s) as well as the scale of the analysis. To facilitate decision-making for environmental compensation projects such as “biodiversity offsets”, we examined whether Japanese ecoregions based on vegetation are correlated with the distribution of cerambycid beetles, using existing cerambycid data collected from Hokkaido to the Nansei Islands in both natural and plantation forests over 1 year in each area. At the national level, the species compositions of beetles were quite distinct in Hokkaido and the Nansei Islands but less so in other areas. The overall pattern of the observed sampling data fit that obtained by previously accumulated local inventories. At the area level (including plantation forests under different management regimes/successional stages and in some cases naturally regenerated mature to old growth forests), no consistent beetle composition patterns were observed, although compositions in natural forests and closed canopy/thinned/old growth plantation forests were sometimes distinct. Therefore, we conclude that when ecoregions are considered during decision-making for “no net-loss or net-gain” biodiversity conservation measures, it is important to examine multiple organisms on various scales using scientific approaches from several perspectives.     

Effects of trap type, placement and ash distribution on emerald ash borer captures in a low density site

Effective methods for early detection of newly established, low density emerald ash borer (Agrilus planipennis Fairmaire) infestations are critically needed in North America. We assessed adult A. planipennis captures on four types of traps in a 16-ha site in central Michigan. The site was divided into 16 blocks, each comprised of four 50- by 50-m cells. Green ash trees (Fraxinus pennsylvanica Marshall) were inventoried by diameter class and ash phloem area was estimated for each cell. One trap type was randomly assigned to each cell in each block. Because initial sampling showed that A. planipennis density was extremely low, infested ash logs were introduced into the center of the site. In total, 87 beetles were captured during the summer. Purple double-decker traps baited with a blend of ash leaf volatiles, Manuka oil, and ethanol captured 65% of all A. planipennis beetles. Similarly baited, green double-decker traps captured 18% of the beetles, whereas sticky bands on girdled trees captured 11% of the beetles. Purple traps baited with Manuka oil and suspended in the canopies of live ash trees captured only 5% of the beetles. At least one beetle was captured on 81% of the purple double-decker traps, 56% of the green double-decker traps, 42% of sticky bands, and 25% of the canopy traps. Abundance of ash phloem near traps had no effect on captures and trap location and sun exposure had only weak effects on captures. Twelve girdled and 29 nongirdled trees were felled and sampled in winter. Current-year larvae were present in 100% of the girdled trees and 72% of the nongirdled trees, but larval density was five times higher on girdled than nongirdled trees.