Walnut
Guides
Acrobasis demotella
Walnut Shoot Moth
Acrobasis demotella, the walnut shoot moth, is a small pyralid moth described by Grote in 1881. Its larvae feed on Juglans (walnut) and Carya (hickory/pecan) species, making it a pest of nut-producing trees. The species occurs across eastern and central North America. It is one of several Acrobasis species associated with hardwood trees in the walnut family.
Acrobasis juglandis
Pecan Leaf Casebearer, Pecan Leaf Casebearer Moth
Acrobasis juglandis is a small pyralid moth commonly known as the pecan leaf casebearer. The species is a significant pest of pecan and walnut trees, with larvae feeding on foliage and nutlets of host plants in the genus Carya and Juglans. Its common name derives from the larval habit of constructing protective cases from leaf material. The species is native to North America and has been documented from Ontario south to Florida and west to New Mexico.
Amyelois transitella
Navel Orangeworm, Navel Orangeworm Moth
The navel orangeworm moth (Amyelois transitella) is a pyralid moth native to the tropical western Hemisphere and southwestern United States. First described from Arizona in 1899, its abundance in California increased dramatically during the first half of the 20th century. It is now the most serious insect pest of almonds and pistachios in California, with larvae feeding directly on nuts and adults capable of introducing fungi that produce aflatoxins. The species has been extensively studied for its chemical ecology, particularly its sex pheromone system, which has enabled practical mating disruption programs in agricultural fields.
Caloptilia blandella
Walnut Caloptilia Moth
Caloptilia blandella is a small moth in the family Gracillariidae, commonly known as the Walnut Caloptilia Moth. It has a wingspan of approximately 9 mm. The species is distributed across eastern North America, with records from Canada (Québec) and several U.S. states including Pennsylvania, Virginia, Maine, Maryland, Texas, and Kentucky. Larvae are leaf miners that feed on shagbark hickory (Carya ovata) and black walnut (Juglans nigra).
Catocala serena
Serene Underwing
Catocala serena, the serene underwing, is a moth in the family Erebidae. It is found in eastern North America from southern Ontario and New England south to Tennessee, and west to Illinois and eastern Wisconsin. Adults are active from July to September with one generation per year. The larvae feed on shagbark hickory (Carya ovata) and black walnut (Juglans nigra).
Catocala subnata
Youthful Underwing
Catocala subnata, commonly known as the youthful underwing, is a large underwing moth in the family Erebidae. First described by Augustus Radcliffe Grote in 1864, this species is characterized by its cryptic forewings that conceal brightly colored hindwings, a defensive trait shared with other members of the genus Catocala. The species has a broad distribution across eastern and central North America, with adults active during mid to late summer. Larvae feed on specific host trees in the walnut family.
Citheronia regalis
Regal Moth, Royal Walnut Moth
Citheronia regalis is a large North American saturniid moth known as the regal moth or royal walnut moth. Its larval stage, the hickory horned devil, is one of the largest caterpillars in North America north of Mexico and is notable for its striking appearance with prominent red and black horns. Adults have vestigial mouthparts and do not feed, living only about a week to mate and lay eggs. The species has a single generation per year throughout most of its range.
Coleophora laticornella
pecan cigar casebearer
Coleophora laticornella, commonly known as the pecan cigar casebearer, is a case-bearing moth in the family Coleophoridae. It is native to North America and has been documented in 263 iNaturalist observations. The species is notable for its economic significance as a pest of pecan and other nut trees.
Conotrachelus retentus
Black Walnut Curculio
Conotrachelus retentus, commonly known as the black walnut curculio, is a true weevil (Curculionidae) native to North America. The species is tightly associated with black walnut (Juglans nigra), with larvae developing inside developing nuts and adults feeding on foliage. Adults exhibit limited dispersal behavior and have been observed to rarely leave their natal tree. The species is considered a pest of walnut production due to damage to nuts and foliage.
Coptodisca
Coptodisca is a genus of small moths in the family Heliozelidae, established by Walsingham in 1895. Species are leafminers whose larvae feed internally on leaves of woody plants, creating distinctive blotch mines. Several species have become invasive pests in Europe, particularly C. lucifluella and C. juglandiella on walnut (Juglans) and related trees. The genus is native to the Nearctic region with approximately 20 described species.
Corythucha juglandis
Walnut Lace Bug
Corythucha juglandis, the walnut lace bug, is a univoltine or bivoltine lace bug (Hemiptera: Tingidae) native to North America and specialized on walnut (Juglans) host plants. Adults overwinter in leaf litter and become active in April or May, synchronizing with host leaf phenology. The species aggregates on the undersides of leaflets for feeding and reproduction. Both adults and nymphs are gregarious. It has been studied in Ontario, Québec, Canada, and southern Illinois, USA, with some geographic variation in voltinism reported.
Eriocampa
woolly sawflies
Eriocampa is a small Holarctic genus of sawflies in the family Tenthredinidae comprising approximately five to ten described extant species. The genus is characterized by larvae that produce conspicuous white waxy secretions, giving them a woolly appearance that likely serves as a defense against predators and parasitoids. Several species are economically significant as defoliators of woody plants, including Eriocampa juglandis (butternut woollyworm) on walnut and hickory, and Eriocampa ovata (woolly alder sawfly) on alder. The genus has a debated taxonomic history, with various classifications placing it in different subfamilies within Tenthredinidae.
Eriocampa juglandis
Butternut Woollyworm, Butternut Woollyworm Sawfly, Butternut Wooly Worm
Eriocampa juglandis, commonly known as the butternut woollyworm, is a sawfly in the family Tenthredinidae. The larvae feed on leaves of butternut, black walnut, and hickory trees, and are notable for their distinctive white, woolly wax coating. Unlike true caterpillars, sawfly larvae possess six or more pairs of prolegs on their abdominal segments. The species has one generation per year, with larvae active in mid-summer and pupation occurring in soil over winter.
Macremphytus
Dogwood Sawflies
Macremphytus is a genus of common sawflies in the family Tenthredinidae, comprising at least four described species. The best-known member is Macremphytus tarsatus, commonly called the dogwood sawfly, which is a significant defoliator of dogwood trees in North America. Sawflies in this genus are herbivorous, with larvae feeding on leaves of woody plants. The genus exhibits distinctive larval traits including waxy secretions and overwintering behaviors in wood.
Panaphis juglandis
Walnut Aphid, Large Walnut Aphid
Panaphis juglandis, the large walnut aphid, is a phloem-feeding pest of walnut trees (Juglans regia). It colonizes exclusively the upper (adaxial) surface of walnut compound leaves, forming dense colonies along the main vascular veins of the outer leaflets. Native to the Old World (Central Asia and southeastern Europe), it has spread across Europe and was introduced to California in the early 20th century. The species reduces tree vigor, nut yield, and quality, and excretes honeydew that promotes sooty mold growth. It forms mutualistic relationships with ant species that tend and protect colonies from predators.
Pityophthorus juglandis
Walnut Twig Beetle
Pityophthorus juglandis is an invasive bark beetle native to the southwestern United States and Mexico that vectors the fungal pathogen Geosmithia morbida, causing thousand cankers disease in walnut trees. The beetle measures approximately 1.5 mm in length and is among the few Pityophthorus species associated with hardwoods. Research has focused extensively on its chemical ecology, including the male-produced aggregation pheromone 3-methyl-2-buten-1-ol and potential semiochemical repellents for management. The species exhibits strong host discrimination during flight, preferentially landing on Juglans species while avoiding most non-host hardwoods.
Rhagoletis completa
Walnut Husk Fly
Rhagoletis completa, the walnut husk fly, is a tephritid fruit fly native to central North America and now established in Europe. It is the most economically significant pest of walnut (Juglans regia) production, causing yield losses up to 80% through larval feeding on husk tissue. Adults emerge over a prolonged period from mid-May to October and are distinguished by a dark triangular wing pattern and yellowish-white scutellum. The species has one generation per year, with larvae pupating in soil and a small proportion entering prolonged dormancy.
Stigmella longisacca
Stigmella longisacca is a pygmy moth in the family Nepticulidae, first described in 1982. It is endemic to California, where its larvae are leaf miners on Juglans species, particularly Juglans californica. The species has a wingspan of 3.2–4.4 mm and appears to have two to three generations per year.
Systena sexnotata
six-spotted flea beetle
Systena sexnotata is a flea beetle in the family Chrysomelidae. Adults feed on walnut foliage (Juglandaceae), while larvae feed on roots. The species is restricted to Central and Western Texas. Body length ranges from 4.8 to 5.5 millimeters.