Chrysodeixis includens

Adults can be distinguished from the similar Rachiplusia nu (sunflower looper) by wing pattern: C. includens has two separated spots on the forewings, while R. nu has two joined kidney-shaped spots. Larvae of the two species are morphologically similar but can be distinguished by spinneret shape (R. nu has a more triangular spinneret, C. includens more conical), though this requires dissection. In practice, R. nu larvae often appear darker with a smoky-blue cast compared to the bright yellow-green of C. includens, and R. nu shows distinct patches of tiny black asperites on the thoracic venters not apparent in C. includens. C. includens larvae have three pairs of prolegs, distinguishing them from true inchworms (Geometridae) which have only two pairs.

Primarily agricultural habitats, especially soybean fields. Also found in other cultivated areas supporting its broad host plant range. The species has been observed in alfalfa, flax, sunflower, and various vegetable crop systems.

Native to the Americas. Found from southern Quebec and southern Ontario through the eastern and southern United States to Central America, South America, the Antilles, and the Galápagos Islands. Established populations occur throughout Brazil and northern Argentina, where it has become an increasingly important pest in recent years. The species is known to be migratory.

Adults are on wing from April to November depending on location. In temperate regions, multiple generations occur during the growing season. In subtropical and tropical regions, continuous breeding is possible.

Highly polyphagous. Larvae feed on foliage of numerous plant species across multiple families. Primary hosts include Glycine max (soybean), Phaseolus vulgaris (common bean), Gossypium hirsutum (cotton), Nicotiana tabacum (tobacco), Solanum lycopersicum (tomato), Brassica oleracea, Lactuca sativa (lettuce), Helianthus annuus (sunflower), Zea mays (maize), Medicago sativa (alfalfa), Arachis hypogaea (peanut), and many others. Young larvae typically feed on lower leaf surfaces between veins, creating "window pane" damage; older larvae consume entire tissues while avoiding veins, resulting in skeletonized foliage.

• Glycine max - primary hostPreferred host; larvae feed on foliage, causing significant defoliation
• Phaseolus vulgaris - hostLarvae feed on foliage
• Gossypium hirsutum - hostLarvae feed on foliage
• Nicotiana tabacum - hostLarvae feed on foliage
• Solanum lycopersicum - hostLarvae feed on foliage
• Helianthus annuus - hostLarvae feed on foliage
• Medicago sativa - hostLarvae feed on foliage

Eggs are laid on leaf undersides, primarily in middle or upper canopy. Larvae pass through five instars; early instars have black head capsules, second instars light brown, later instars lightly colored with distinct bristles. Larvae display characteristic looping movement due to reduced proleg number (three pairs). Pupation occurs in soil or leaf litter. Multiple generations per year in favorable climates. Developmental rate varies with temperature, instar, and larval weight.

Larvae exhibit characteristic looping locomotion due to having only three pairs of prolegs, arching the body to bring the rear prolegs forward to meet the thoracic legs. Young larvae feed on lower leaf epidermis between veins; older larvae skeletonize leaves by consuming tissue while avoiding vascular bundles. Adults are nocturnal and migratory. Females exhibit clear oviposition preferences for canopy position based on plant growth stage.

Significant agricultural pest causing defoliation and yield loss in soybean and other crops. Serves as host for multiple parasitoid species including Trichogramma spp. (egg parasitoids), Microplitis demolitor and Copidosoma floridanum (larval parasitoids), and Tetrastichus howardi (pupal parasitoid). Preyed upon by generalist predators including Podisus maculiventris (spined soldier bug) and Tadarida brasiliensis (Mexican free-tailed bat). Population dynamics influenced by entomopathogenic fungi under moist conditions.

Major economic pest of soybean in North and South America. Larval feeding causes defoliation and yield reduction; damage thresholds exceed approximately 15% foliage loss during reproductive stages. Has developed resistance to most insecticides used for control, complicating management. Subject of biological control research using nucleopolyhedrovirus (ChinNPV), entomopathogenic nematodes (Steinernema carpocapsae), and parasitoid conservation. Bt-traited soybeans have been developed for management. Misidentification with similar species (especially Rachiplusia nu) leads to control failures due to differing pesticide susceptibilities.

• Rachiplusia nuLarval morphology extremely similar; adults distinguished by joined versus separated forewing spots; larvae distinguished by spinneret shape and subtle coloration differences; differs in pesticide susceptibility and geographic distribution
• Trichoplusia ni (cabbage looper)Larval morphology similar with three proleg pairs; distinguished by host preferences and geographic patterns; C. includens has black true legs, different head capsule coloration in early instars
• Anticarsia gemmatalis (velvetbean caterpillar)Co-occurs in soybean; distinguished by having five pairs of prolegs (not looping), different egg morphology (flattened spherical, pinkish with age), and different larval coloration and movement
• Spodoptera spp. (armyworms)Co-occur in soybean; distinguished by four pairs of prolegs, presence of pinaculae with stout setae, and different head capsule markings
• Helicoverpa zea (soybean podworm)Co-occurs in soybean; distinguished by larger size, different egg morphology (barrel-shaped, laid on multiple plant parts including pods), and pod-feeding behavior in addition to foliage feeding

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Scientists Reveal New Method to Characterize Physiological Responses to Parasitism | Bug Squad
• ID Challenge #14 | Beetles In The Bush
• “Sunflower looper” – Rachiplusia nu | Beetles In The Bush
• Noctuidae | Beetles In The Bush | Page 2
• A Revision of Soybean Caterpillar Pest Information for U.S. Soybean
• owlet moths | Beetles In The Bush
• Chrysodeixis includens nucleopolyhedrovirus (ChinNPV) Affects on Immature Stages of Chrysodeixis includens (Lepidoptera: Noctuidae)
• Soybean Looper Chrysodeixis includens (Walker) (Insecta: Lepidoptera: Noctuidae)
• Host plants of Chrysodeixis includens (Walker) (Lepidoptera, Noctuidae, Plusiinae)
• Parasitism of Tetrastichus howardi (Ollif, 1893) (Hymenoptera: Eulophidae) on Chrysodeixis includens (Walker, [1858]) (Lepidoptera: Noctuidae) pupae at different ages
• Population dynamics, vertical distribution and natural parasitism of eggs ofChrysodeixis includensbyTrichogrammaspp.in soybean
• Sublethal effects of Bacillus thuringiensis biopesticides and insecticides combinations on Chrysodeixis includens larvae: insights on pest management
• Generation of Variability in Chrysodeixis includens Nucleopolyhedrovirus (ChinNPV): The Role of a Single Variant
• Partial Life History ofChrysodeixis includens(Lepidoptera: Noctuidae) on Summer Hosts
• The Effects of Adjuvants on Steinernema Carpocapsae Efficacy Against Chrysodeixis Includens and Suspension Stability.