Forest-pest
Guides
Lophocampa caryae
Hickory Tussock Moth, Hickory Halisidota, Hickory Tiger Moth
Lophocampa caryae is a tiger moth in the family Erebidae, widely distributed across eastern North America. The species has one generation per year, with adults flying in May and June. The caterpillar is covered in dense white and black hair tufts and can cause contact dermatitis in humans through its barbed setae. Despite anecdotal claims of venomous properties, no venom has been isolated; adverse reactions are characterized as irritant contact dermatitis.
Lymantria dispar
spongy moth, gypsy moth
Lymantria dispar is a forest-defoliating moth native to Europe and Asia, now invasive across multiple continents including North America. The species is notable for pronounced sexual dimorphism in adults and variable flight capability among subspecies—females of the European subspecies (L. d. dispar) are flightless, while Asian subspecies possess flight-capable females. Larvae are polyphagous and have been documented feeding on over 500 plant species. The species ranks among the world's most destructive invasive forest pests, with documented outbreaks exceeding 2.5 million caterpillars per hectare.
Macaria bicolorata
bicolored angle, Southern Pine and Cypress Angles
Macaria bicolorata, commonly known as the bicolored angle, is a geometrid moth native to Eastern North America. Adults are active from May through August, with timing varying by location. The species has a wingspan of approximately 30 mm. Larvae feed on Pinus species, establishing a specific host relationship with conifers.
Malacosoma
Tent Caterpillar Moths
Malacosoma is a genus of tent caterpillar moths in the family Lasiocampidae, first described by Jacob Hübner in 1820. Larvae are commonly known as tent caterpillars and are recognized for their communal nesting behavior in silken tents. The genus includes both oligophagous species with restricted host ranges and polyphagous species with broader diets. Several species are significant forestry pests capable of causing large-scale defoliation across North America and Eurasia.
Megarhyssa nortoni
Norton's giant ichneumonid wasp, western giant ichneumonid wasp
Megarhyssa nortoni is a large ichneumonid wasp native to North America, with two recognized subspecies occupying western and eastern ranges. Females possess an extraordinarily long ovipositor reaching 51–76 mm, used to parasitize horntail wasp larvae deep within wood. Despite their formidable appearance, they are harmless to humans and do not sting. The species has been introduced to several countries as a biological control agent for forest pest horntails.
Melalgus
horned powder-post beetles
Melalgus is a genus of beetles in the family Bostrichidae, commonly referred to as horned powder-post beetles. The genus was established by Dejean in 1833 and contains more than 20 described species. Members of this genus are wood-boring beetles that contribute to the degradation of dead wood in forest ecosystems. The common name "horned" refers to a distinctive cephalic projection present in many species.
Monarthrum
Monarthrum is a genus of bark beetles in the family Curculionidae, containing approximately five described species. These beetles are associated with dying and dead wood, particularly oak, and exhibit ambrosia beetle characteristics including attraction to host volatiles and potential fungal symbiosis. The genus has been studied for its chemical ecology, with specific compounds identified as attractants for monitoring purposes.
Monarthrum scutellare
ambrosia beetle
Monarthrum scutellare is a scolytine weevil (Coleoptera: Curculionidae: Scolytinae) native to North America. It is an ambrosia beetle, a guild that cultivates fungal symbionts within wood galleries rather than feeding directly on plant tissues. The species has been documented in British Columbia, Canada, where it has been detected using a combination of ethanol and synthetic 3-hydroxyoctan-2-one lures. Like other Monarthrum species, it poses potential threats as an invasive pest due to its cryptic lifestyle and association with forest ecosystems.
Monochamus carolinensis
Carolina Pine Sawyer
Monochamus carolinensis is a longhorn beetle in the subfamily Lamiinae, commonly known as the Carolina Pine Sawyer. It is a significant vector of the pinewood nematode Bursaphelenchus xylophilus, the causative agent of pine wilt disease. The species is native to North America, occurring in Canada and the United States, and has been detected in China. Adults are attracted to blacklights and are associated with pine forests.
Monochamus maculosus
spotted pine sawyer
Monochamus maculosus, the spotted pine sawyer, is a longhorned beetle native to North America. It was formerly known as Monochamus mutator. Adults are attracted to monochamol, a sex-aggregation pheromone produced by males. The species breeds in stressed or recently dead conifers, with larvae tunneling in phloem and sapwood. It is a primary vector of the pinewood nematode, the causal agent of pine wilt disease.
Monsoma
green alder sawfly (for M. pulveratum)
Monsoma is a genus of common sawflies in the family Tenthredinidae, containing at least two described species. The genus includes M. pulveratum, known as the green alder sawfly, which has been identified as a potential forest pest in the Pacific Northwest region of the United States. Species in this genus are associated with forest habitats.
Monsoma pulveratum
green alder sawfly
Monsoma pulveratum, known as the green alder sawfly, is a species of common sawfly in the family Tenthredinidae. Native to Europe, it has been accidentally introduced to North America and is documented in the Pacific Northwest region of the United States as well as parts of Canada. The species has been identified as a potential forest pest in its introduced range.
Neoclytus acuminatus
Red-headed Ash Borer, Red-necked Ash Borer
Neoclytus acuminatus, commonly known as the red-headed ash borer, is a North American longhorn beetle in the family Cerambycidae. Adults measure 12–16 mm in length and exhibit striking wasp-mimic coloration with reddish-brown bodies marked by four contrasting yellow bands. The species develops in dead or dying hardwood trees, particularly ash, hickory, and oak, where larvae feed on sapwood. Multiple generations may occur annually in warmer regions. Adults emerge in early spring and are frequently attracted to ethanol-based baits. The species has expanded beyond its native range through human-mediated transport of wood materials and is now established in parts of Europe.
Neodiprion
Neodiprion is a genus of conifer sawflies in the family Diprionidae, containing approximately 25 species native to North America. Larvae are specialized folivores of pine needles, with most species exhibiting strong host associations with particular Pinus species. Several species, including N. lecontei and N. sertifer, are significant forest pests capable of causing extensive defoliation during outbreak years. The genus is distinguished from related sawflies by morphological and ecological traits associated with conifer specialization.
Neodiprion compar
redheaded pine sawfly
Neodiprion compar is a conifer sawfly in the family Diprionidae, commonly known as the redheaded pine sawfly. The species is native to eastern North America and feeds primarily on pine needles. Larvae are gregarious and can cause significant defoliation during outbreaks, though populations are typically moderated by natural enemies. The species is one of approximately 25 conifer sawfly species found in eastern U.S. forests.
Neodiprion excitans
Black-headed Pine Sawfly
Neodiprion excitans, commonly known as the Black-headed Pine Sawfly, is a conifer-feeding sawfly in the family Diprionidae. It is native to eastern North America, with documented populations in North Carolina and surrounding regions. Like other members of its genus, it is a folivore that feeds on pine needles and can cause significant defoliation during outbreak conditions. The species has been studied for its population dynamics and ecological interactions in pine forest ecosystems.
Neodiprion fabricii
Fabricius's Sawfly
Neodiprion fabricii is a conifer sawfly species in the family Diprionidae, native to eastern North America. The larvae are folivores that feed on pine needles, with young larvae consuming partial needles and older larvae eating entire needles. This species is one of approximately 25 conifer sawfly species found in eastern U.S. forests and occasionally contributes to localized defoliation events. Adults are stingless wasps with a saw-like ovipositor used to insert eggs into conifer foliage.
Neodiprion nanulus
Red Pine Sawfly
Neodiprion nanulus, commonly known as the Red Pine Sawfly, is a conifer-feeding sawfly in the family Diprionidae. It is a specialist herbivore associated with red pine (Pinus resinosa). The species has been documented in the Maritime Provinces of Canada, with an isolated infestation studied near Fredericton, New Brunswick. Like other members of the genus, it likely undergoes larval development in gregarious groups and overwinters in cocoons in the duff beneath host trees.
Neodiprion taedae
Neodiprion taedae is a conifer sawfly species in the family Diprionidae, described by Ross in 1955. Like other members of the genus Neodiprion, it is a folivorous herbivore whose larvae feed on pine needles. The species is part of a diverse assemblage of conifer sawflies in eastern North America, where outbreaks can cause significant defoliation of pine forests. It is one of approximately 25 Neodiprion species documented in eastern U.S. forests.
Nepytia
false hemlock loopers, false pine loopers
Nepytia is a genus of geometrid moths (loopers) in the family Geometridae, established by George Duryea Hulst in 1896. The genus includes at least 13 described species distributed in North America. Several species, notably N. janetae and N. freemani, have been documented as forest defoliators capable of outbreak population dynamics that cause significant damage to coniferous trees. The genus exhibits considerable variation in life history traits, with some species being summer feeders and others, uniquely among studied Nepytia, feeding during autumn and winter at high elevations.
Nepytia freemani
Western False Hemlock Looper
Nepytia freemani is a geometrid moth known as the western false hemlock looper, described by Eugene G. Munroe in 1963. The species has a one-year life cycle, overwintering as eggs with larvae emerging in mid-May, feeding through summer, and pupating in late July. Adults appear in August and September. The species has been documented reaching outbreak proportions, with a notable outbreak occurring in north central Utah from 1965 to 1967.
Nepytia janetae
Nepytia janetae is a geometrid moth species that has transitioned from an innocuous, poorly studied insect to a significant forest pest in the southwestern United States. Since 1996, four major outbreaks have caused extensive defoliation and mortality of conifer trees across tens of thousands of acres in Arizona and New Mexico mountain ranges. The species exhibits an unusual life history as a univoltine, autumn- and winter-feeding looper at high elevations where temperatures regularly approach or fall below 0°F. Outbreaks appear associated with reduced snowpack, though the precise climatic mechanisms remain unclear.
Obolodiplosis robiniae
locust gall midge, black locust gall midge
Obolodiplosis robiniae is a small gall midge (Diptera: Cecidomyiidae) native to eastern North America that has become a significant invasive pest in Eurasia. The species is monophagous on Robinia species, particularly black locust (Robinia pseudoacacia), forming distinctive leaf margin roll galls through gregarious larval feeding. First described from Pennsylvania in 1847, it was detected in Asia in 2002-2003 (Japan, Korea) and Europe in 2003 (Italy), subsequently spreading explosively to 26 European countries and much of China. Climate modeling predicts substantial northward range expansion under warming scenarios, with suitable habitat potentially increasing by 35% by 2070. The midge reduces host tree growth and productivity, causes early leaf abscission, and facilitates secondary pest attacks by wood-boring beetles.
Odontopus calceatus
Yellow Poplar Weevil, Sassafras Mining Weevil, Tuliptree Leafminer, Tulip Tree Weevil, Magnolia Leaf Miner
A small weevil in the family Curculionidae, known for feeding on and mining the leaves of tulip tree (Liriodendron tulipifera), sassafras (Sassafras albidum), and magnolia species. Adults are most visible in spring when they emerge to feed on host foliage, causing distinctive notching damage along leaf edges. The species is widespread in eastern North America and occasionally reaches outbreak densities that cause noticeable defoliation.
Oligotrophus
Oligotrophus is a genus of gall midges (Cecidomyiidae: Diptera) established by Latreille in 1804. Species are gall-forming insects that induce abnormal plant growths on various host plants, with documented associations to birch (Betulaceae) and juniper (Cupressaceae). The genus contains univoltine species with specialized life cycles tied to host phenology. Several species have been studied for their economic impact on ornamental and forest trees.
Oncideres cingulata
twig girdler, Eastern Twig Girdler
Oncideres cingulata, commonly known as the twig girdler, is a cerambycid beetle notable for its distinctive reproductive behavior where adult females girdle twigs of host trees to create larval habitat. The beetle is brownish-gray, 13–16 mm in length, with antennae 13–25 mm long. Adults are active in late summer and fall, and females cut through bark and wood of small branches (6–12.7 mm diameter) before laying eggs in the severed portion. Larvae develop within the fallen girdled twigs, feeding on woody tissue, and complete a single yearly generation. The species is economically significant as a pest of pecan plantations and other hardwood trees.
Operophtera bruceata
Bruce spanworm, Bruce Spanworm Moth, native winter moth, hunter's moth
Operophtera bruceata is a native North American geometrid moth commonly known as the Bruce spanworm. Females are wingless and flightless, while males have fully developed wings with a 25–30 mm wingspan. The species is notable for forming a documented clinal hybrid zone with the invasive congener winter moth (O. brumata) in the northeastern United States. Population outbreaks have caused significant defoliation of deciduous forests, with one outbreak in Alberta peaking in 1958 at approximately 50,000 square miles of moderate to heavy infestation.
Operophtera brumata
Winter Moth
Operophtera brumata, the winter moth, is a geometrid moth native to Europe and the Near East that has been introduced to North America. It is notable among temperate Lepidoptera for adult activity during late fall and early winter. Females are flightless, while males are fully winged. The species is a significant pest of deciduous trees and an important food source for birds such as Blue Tits, which feed their young almost exclusively on winter moth caterpillars. The USA National Phenology Network includes this species in its Pheno Forecast program to aid pest management.
Ophelimus maskelli
eucalyptus gall wasp, Australian Eucalyptus Leafgall Wasp
Ophelimus maskelli is a minute chalcid wasp (approximately 1 mm long) native to Australia and New Zealand that has become invasive across multiple continents. Females oviposit on immature eucalyptus leaves, inducing leaf galls that host developing larvae. Heavy infestations cause widespread defoliation and growth loss in eucalyptus plantations. The species has been successfully suppressed in some regions through biological control using parasitoids, particularly Closterocerus chamaeleon and Stethynium ophelimi.
Orchestes
flea weevils
Orchestes is a genus of flea weevils (Curculionidae) comprising six species in North America and additional species in Eurasia. Members are small beetles (2–4 mm) associated with woody host plants, particularly trees in Ulmaceae and Fagaceae. The genus was historically confused with Rhynchaenus, from which it has been redefined. Several species are significant pests: O. steppensis is a destructive invasive of elms in China and North America, O. alni (European elm flea weevil) damages elms in Europe and North America, and O. fagi attacks beech trees. Larval habits vary—most are leaf miners, though O. hustachei uniquely parasitizes aphid galls.
Orchestes fagi
Beech leaf-mining weevil, beech leaf-miner beetle
Orchestes fagi is a small weevil species native to Europe that has become invasive in North America, where it attacks American beech (Fagus grandifolia). The larvae mine the leaves of beech trees, while adults undergo an extended diapause of eight to nine months, overwintering on tree boles. The species has spread through eastern Nova Scotia, Canada, with human-assisted transport via firewood and timber implicated in its range expansion.
Orgyia
tussock moths, vapourer moths
Orgyia is a genus of tussock moths in the family Erebidae, characterized by pronounced sexual dimorphism: males are fully winged and diurnal, while females are wingless with reduced, scale-like wings and remain flightless. The genus was established by Ochsenheimer in 1810 and contains cosmopolitan species distributed across most global regions except the Neotropics. Several species are significant forest and agricultural pests, notably Orgyia pseudotsugata (Douglas-fir Tussock Moth), which undergoes periodic outbreaks in western North America.
Orgyia pseudotsugata
Douglas-fir tussock moth
A western North American tussock moth known for periodic population outbreaks that cause significant defoliation of conifer forests. Males are winged and grayish-brown with feathery antennae, while females are flightless with rudimentary wings. Caterpillars are distinctive with red spots, white spines, and prominent red-tipped white tussocks. The species undergoes cyclical outbreaks every 8-12 years that can persist for up to four years.
Orgyia vetusta
Western Tussock Moth
Orgyia vetusta, the Western Tussock Moth, is a species of tussock moth in the family Erebidae. It is native to western North America, ranging from British Columbia through the Pacific States to New Mexico, with an isolated population in Idaho. The species is known to undergo periodic outbreaks, and females are wingless while males possess functional wings. Larvae are notable for their distinctive hair tufts and tussocks.
Orthotomicus erosus
Mediterranean pine engraver
Orthotomicus erosus, the Mediterranean pine engraver, is a bark beetle native to the Mediterranean region, southern Europe, Asia, and North Africa. It is primarily a secondary pest that colonizes stressed, weakened, or recently dead pine trees, but can reach outbreak levels and attack healthy trees during drought conditions or following fire. The species has expanded its range through domestic and international trade, with established populations in South America (Argentina and Uruguay) and South Africa. It vectors multiple ophiostomatoid fungi, including Ophiostoma ips, which contribute to blue staining and tree decline.
Oxydia
Oxydia is a genus of geometrid moths in the family Geometridae, first described by Achille Guenée in 1857. Species in this genus are distributed across the Americas, with several species recognized as forest pests of economic importance. The genus includes defoliator species that attack conifers, eucalyptus, and other woody plants. Larvae are commonly known as loopers or measuring worms due to their characteristic looping gait.
Pachylobius
pine weevils
Pachylobius is a genus of pine weevils in the family Curculionidae, established by LeConte in 1876. The genus contains at least two described species: Pachylobius picivorus (pitch-eating weevil) and Pachylobius stupidus. Species in this genus are associated with coniferous hosts and have been documented as pests of pine regeneration in forest ecosystems.
Paleacrita
spring cankerworm moths
Paleacrita is a genus of geometer moths (Geometridae) containing at least three described species, including the widespread spring cankerworm (Paleacrita vernata). The genus was established by Riley in 1876. Species in this genus are notable for having flightless females in at least some species, a trait that influences their dispersal biology and seasonal activity patterns.
Pantographa limata
Basswood Leafroller Moth
Pantographa limata, commonly known as the basswood leafroller moth, is a crambid moth native to eastern North America. Adults have a wingspan of approximately 38 mm. The larvae are leafrollers that feed on Tilia species, constructing shelters by rolling host plant leaves.
Paraclemensia acerifoliella
Maple Leafcutter Moth
Paraclemensia acerifoliella is a small moth in the family Incurvariidae, known as the maple leafcutter moth. It is native to North America with a range spanning southeastern Canada, the northeastern United States, and south along the Appalachians to western North Carolina. The species has one generation per year, with adults active in spring. Larvae are leaf miners that later construct portable cases from cut leaf pieces.
Patelloa
Patelloa is a genus of tachinid flies established by Townsend in 1916. At least 17 species are recognized, distributed primarily in North America. One well-studied species, P. pachypyga, is a larval parasitoid of the forest tent caterpillar (Malacosoma disstria) and uses host-damaged foliage as a kairomone cue for host location.
Patelloa pachypyga
Patelloa pachypyga is a tachinid fly and a principal larval parasitoid of the forest tent caterpillar (Malacosoma disstria) in Canada. The species locates hosts using olfactory cues, including volatiles from host frass and specific host plant species. It has been documented to preferentially locate hosts on aspen poplar (Populus tremuloides) compared to balsam poplar (Populus balsamifera).
Phigalia titea
Half-wing Moth, Spiny Looper
Phigalia titea, commonly known as the Half-wing Moth or Spiny Looper, is a geometrid moth native to eastern North America. Adult males have fully developed wings with an average wingspan of approximately 34 mm, while females are wingless (apterous). The species is notable for its exceptionally early adult activity period in late winter and early spring, making it one of the first moths to appear each year. Larvae are polyphagous loopers (inchworms) that feed on a wide variety of deciduous hardwood trees and can cause significant defoliation during outbreak years.
Phloeosinini
Phloeosinini is a tribe of bark beetles within the subfamily Scolytinae, comprising at least 16 genera including the economically significant genus Phloeosinus. Members are wood-boring beetles primarily associated with conifer hosts across five families: Araucariaceae, Cupressaceae, Pinaceae, Podocarpaceae, and Taxaceae. The tribe includes species with invasive potential that are readily transported internationally via wood products and packaging materials.
Phloeosinus
cedar bark beetles, cypress bark beetles
Phloeosinus is a genus of bark beetles (Curculionidae: Scolytinae) comprising at least 20 described species. Species in this genus are specialized on conifers in the family Cupressaceae, including genera such as Cupressus, Thuja, Juniperus, and Chamaecyparis. Several species have become significant invasive pests, causing economic damage to ornamental trees and forest ecosystems. The genus exhibits specialized chemical ecology, with species using host plant volatiles and pheromones for mate and host location.
Phloeosinus armatus
Phloeosinus armatus is a bark beetle in the subfamily Scolytinae, the largest species in its genus. Native to the Middle East and eastern Mediterranean, it has been introduced to Italy, Russia, and North America. The species colonizes Cupressus sempervirens (Mediterranean cypress), forming gallery systems on trunks and large branches. It acts as a vector for phytopathogenic fungi, including Seiridium cardinale, the agent of cypress canker disease.
Phloeosinus cupressi
cypress bark beetle
Phloeosinus cupressi is a crenulate bark beetle native to North America that has become invasive in Australia and New Zealand. It poses a serious threat to Cupressus trees and related conifers, with potential ecological and economic impacts globally. Climate change is projected to expand its suitable habitat northward by approximately 18% under RCP6.0 scenarios.
Phloeosinus punctatus
western cedar bark beetle
Phloeosinus punctatus is a bark beetle in the family Curculionidae, subfamily Scolytinae, known as the western cedar bark beetle. The species colonizes giant sequoia (Sequoiadendron giganteum) and California incense-cedar (Calocedrus decurrens) in the Sierra Nevada mountains of California. Females initiate gallery construction and mate monogamously. The beetle undergoes four larval instars, typically producing one generation per year under natural conditions. It has been observed to contribute to branch mortality in giant sequoia, particularly when trees are under environmental stress.
Phloeosinus sequoiae
Redwood Bark Beetle
Phloeosinus sequoiae is a small bark beetle in the family Curculionidae, commonly known as the Redwood Bark Beetle. The species was described by Hopkins in 1903 and is associated with Sequoia and Sequoiadendron species. It belongs to a genus of crenulate bark beetles that tunnel beneath bark of conifers.
Phorocera
Phorocera is a genus of tachinid flies comprising approximately 13 described species. Species in this genus are parasitoids of various insect hosts, particularly sawflies and lepidopteran larvae. Several species have been investigated for biological control of forest pests, including conifer-feeding sawflies and the spruce budworm. The genus is characterized by specific adult and immature morphological features used in identification.