Thyridopteryx

Stephens, 1835

bagworm moths

Species Guides

2

Thyridopteryx is a of bagworm moths (Psychidae) comprising five described . The genus is best known for T. ephemeraeformis, the evergreen bagworm or North American bagworm, a significant pest of ornamental and landscape plants. Larvae construct protective cases from silk and plant fragments, which they carry throughout their development. The genus exhibits unusual : males are winged and capable of , while females are wingless and remain within their cases for life.

Thyridopteryx meadii by (c) Henrik Kibak, some rights reserved (CC BY), uploaded by Henrik Kibak. Used under a CC-BY license.Thyridopteryx meadii by (c) CK2AZ, some rights reserved (CC BY), uploaded by CK2AZ. Used under a CC-BY license.Thyridopteryx by (c) John B., some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Thyridopteryx: /θaɪˌrɪdəpˈtɛrɪks/

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Identification

Members of Thyridopteryx are distinguished from other Psychidae by their larval case and associations. Larval cases are typically conical, constructed from silk interwoven with plant fragments oriented with ends directed downward. Cases of T. ephemeraeformis often resemble small pinecones, leading to misidentification as plant parts. males are small, dark with clear wings; females are maggot-like, wingless, and never leave their cases.

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Habitat

Larvae occur on woody plants in urban, residential, and natural landscapes. T. ephemeraeformis has been documented on over 50 of deciduous and evergreen trees and shrubs, with particular affinity for Juniperus and Thuja .

Distribution

Eastern North America, with T. ephemeraeformis extending from the northeastern United States through the southeastern states and into the Midwest. The has been introduced to other regions; T. ephemeraeformis has been recorded in Bangladesh and southern Australia.

Diet

Larvae are highly foliage feeders. T. ephemeraeformis has been documented feeding on over 125 of woody plants across 45 , including juniper, arborvitae, spruce, pine, Leyland cypress, maple, sycamore, and numerous ornamental species.

Host Associations

  • Juniperus virginiana - primary eastern red cedar
  • Thuja occidentalis - primary arborvitae
  • ×Cupressocyparis leylandii - Leyland cypress
  • Psidium guajava - guava (Bangladesh record)
  • Thuja standishii - arborvitae/juniper (Bangladesh record)
  • Ixora grandiflora - rangan/jungle geranium (Bangladesh record)
  • Mussaenda philippica - mussaenda (Bangladesh record)
  • Acalypha wilkesiana - copperleaf (Bangladesh record)
  • Lawsonia inermis - henna (Bangladesh record)
  • Mangifera indica - mango (Bangladesh record, no significant damage observed)
  • Punica granatum - pomegranate (Bangladesh record, no significant damage observed)
  • Areca catechu - betel nut (Bangladesh record, no significant damage observed)

Life Cycle

overwinter inside the maternal case. larvae emerge in late spring (mid-May in Kentucky), disperse by ballooning on silk threads, and construct individual cases from silk and plant material. Cases are enlarged as larvae grow through instars. occurs within the case in late summer. Males emerge as winged and fly to locate females; females remain in their cases, release to attract males, and mate without leaving the case. After mating, females lay 200–1000+ eggs within the case, then exit, fall to the ground, and die.

Behavior

larvae disperse by ballooning (silking) on wind currents. Approximately 75% of dispersing larvae construct cases before ballooning. Case-carrying larvae balloon primarily in the afternoon; caseless larvae balloon mainly in the morning. Larvae exhibit selection : they readily settle on arborvitae and juniper foliage but tend to disperse from maple and other deciduous hosts. Cases function as thermal modifiers, maintaining temperatures significantly above ambient in both sun and shade. Male and female larvae exhibit differential stratification on host trees: females gradually ascend the crown while males remain at lower heights.

Ecological Role

Larvae are significant defoliators of ornamental and landscape plants. Severe can kill evergreen in a single season. The serves as host for including Itoplectis conquisitor (primary parasitoid), Calliephialtes grapholithae, and other ichneumonid and chalcidoid parasitoids. Larval cases provide for associated fungi.

Human Relevance

T. ephemeraeformis is a major pest of urban and suburban landscaping, causing substantial economic damage to nurseries and residential plantings. Control methods include manual removal of cases (92% efficacy demonstrated), applications (Bacillus thuringiensis for small larvae, spinosad for larger larvae), and using synthetic (1-methylbutyl decanoate, which suppressed mating by 87% in field trials). The is monitored by the USA National Network Pheno Forecast system to optimize management timing.

Similar Taxa

  • Dahlica triquetrellaBoth are Psychidae with case-bearing larvae, but Dahlica cases are much smaller, composed of detritus rather than oriented plant fragments, and often mistaken for dirt or wood particles.
  • Chalcoela iphitalisLarvae occur in similar ( nests) and may be confused, but C. iphitalis is a crambid with predatory larvae that feed on wasp , not plant material.

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