Tuberolachnus salignus

Distinguished from other aphids by its exceptional size (largest known aphid species), the prominent single dorsal tubercle, and rows of black dots along the body. The combination of large size, dark coloration with grayish-gold abdominal hairs, and the characteristic thorn-like tubercle separates it from other Lachninae aphids. Winged and wingless forms occur; winged forms have clear wings with dark brown forewing edges.

Almost entirely dependent on willow trees (Salix spp.), living on bark and feeding on phloem sap. Found on stems and branches, with seasonal movement to shoot tips for feeding. Survives year-round on host trees, with spring populations retreating behind bark or into soil during harsh conditions. In New Zealand, also recorded on apple, pear, and poplar trees near infested willows.

Cosmopolitan distribution; originated in Asia (likely Japan/Korea region) and now present on all continents except Antarctica. Established in Europe, North America, South America (Patagonia), Australia, and New Zealand (first detected December 2013 in Auckland, now widespread). In New Zealand, present wherever willow species occur. Also recorded in India (Kashmir) on apple.

Most active in late summer and early autumn when populations peak. Generation time of 2-3 weeks depending on temperature. Year-round activity with reduced fecundity in colder months. In spring, colonies often not visible as aphids retreat to protected locations. In some regions, late September appearance on willow shoots with population buildup through late February.

Obligate phloem feeder on willow (Salix) species, including white willow (Salix alba), common sallow (Salix cinerea), and Indian willow (Salix tetrasperma). Also recorded on poplar (Populus spp.), apple (Malus domestica), pear (Pyrus spp.), and quince (Cydonia oblonga). Feeds during warmer daylight hours, preferring shoot tips where plant tissue is softer. Ingests large volumes of sucrose-rich, amino acid-poor sap, excreting excess sugar as honeydew.

• Salix alba - primary hostwhite willow
• Salix cinerea - primary hostcommon sallow
• Salix tetrasperma - primary hostIndian willow
• Salix fragilis - hostcrack willow
• Populus spp. - secondary hostpoplars
• Malus domestica - secondary hostapple; recorded in New Zealand and India
• Pyrus spp. - secondary hostpear
• Cydonia oblonga - secondary hostquince

Obligate parthenogenesis with no sexual phase; all individuals are female. Reproduction via viviparity (live birth of nymphs) during favorable conditions. Four nymphal instars before adulthood; development from nymph to adult takes approximately two weeks at optimal temperatures (17.5-22.5°C). Adults live approximately five weeks. Fecundity of 35-71 offspring per female. In autumn, females switch to oviparity, laying thousands of black eggs on branches as the overwintering stage. Eggs hatch in spring when host trees become sappy.

Feeds preferentially during daylight and warmer hours, climbing to shoot tips to access softer plant tissue. Uses paired stylets to pierce phloem: one injects saliva, the other ingests sap-saliva mixture. Forms dense colonies on host stems. Exhibits temperature-dependent feeding rates to compensate for nutritionally dilute phloem sap. Produces copious honeydew (estimated 1517 kg/ha/season in some regions), which attracts ants, wasps, bees, and other insects that feed on the excreted sugars but not the aphids themselves.

Significant honeydew producer, creating localized sugar resource that supports diverse insect community including ants, wasps, bees, and flies. Honeydew deposition alters soil biota and biochemical properties beneath host trees, increasing microbial biomass, respiration, and mesofauna abundance. Serves as prey for lady beetles, lacewings, hover fly larvae, and parasitic wasps. In invasive range, disrupts native food webs and supports invasive social wasp populations (Vespula spp.) through carbohydrate subsidy.

Invasive pest of willow plantations used for biomass production, land stabilization, and soil erosion control. In New Zealand, threatens willow-based apiculture: honeydew foraged by honeybees causes honey crystallization in combs and reduces bee health and honey quality. Infestation of apple orchards near willow trees causes tree decline, yellowing leaves, stunted growth, reduced fruit production, and sooty mold growth. Subject of biological control efforts using introduced parasitoid Pauesia nigrovaria in New Zealand.

• Longistigma caryaeAlso called 'giant bark aphid' and among largest North American aphids; distinguished by occurrence on oak, hickory, walnut, and beech rather than willow, and lacking the prominent dorsal tubercle characteristic of T. salignus
• Lachnus spp.Related aphids in same tribe Lachnini; distinguished by smaller size, different host associations, and lack of the distinctive large dorsal tubercle

• invasive species
• parthenogenesis
• phloem feeder
• honeydew producer
• willow pest
• viviparity
• cosmopolitan distribution

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• ‘Twas two weeks before Christmas – Giant bark aphids, Longistigma caryae and giant willow aphids, Tuberolachnus salignus — Bug of the Week
• ‘Twas the week before Christmas: Giant bark aphids, Longistigma caryae, and giant willow aphids, Tuberolachnus salignus — Bug of the Week
• Archive — Bug of the Week
• ‘Twas the week before Christmas: Giant bark aphids, Longistigma caryae, and giant willow aphids, Tuberolachnus salignus — Bug of the Week
• Studies On the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae)
• Population genetics of Tuberolachnus salignus , an obligate parthenogenetic aphid
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• Studies On the Feeding and Nutrition ofTuberolachnus Salignus(Gmelin) (Homoptera, Aphididae)
• Monitoring giant willow aphid (<i>Tuberolachnus salignus</i>) on apple trees in close proximity to infested willows
• Honeydew Deposition by the Giant Willow Aphid (Tuberolachnus salignus) Affects Soil Biota and Soil Biochemical Properties
• Direct and Indirect Impacts of the Tuberolachnus salignus (Hemiptera: Aphididae) Invasion in New Zealand and Management Alternatives
• Seasonal abundance of Tuberolachnus salignus and its effect on flowering of host willows of varying susceptibility
• The potential of harlequin ladybird beetle Harmonia axyridis as a predator of the giant willow aphid Tuberolachnus salignus: voracity, life history and prey preference
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• Host selection and performance of the giant willow aphid, Tuberolachnus salignus Gmelin – implications for pest management
• Host specificity testing of Pauesia nigrovaria (Hymenoptera: Braconidae: Aphidiinae) for classical biological control of Tuberolachnus salignus (Hemiptera: Aphididae: Lachninae) in New Zealand
• Honeydew production by the giant willow aphid (Tuberolachnus salignus, Hemiptera: Aphididae) and its effect on foraging yellowjackets (Hymenoptera: Vespidae)