Spodoptera eridania

Adults are distinguished from other Spodoptera species by the combination of gray-brown forewings with variable pattern (including presence or absence of central bean-shaped spot) and opalescent white hind wings. Larvae are distinguished from similar species by the position of the dark lateral spot on the first abdominal segment (versus mesothorax in S. exigua), the interruption of the subspiracular light-colored line by the black marking on the first abdominal segment (line is continuous in S. cosmioides), and the larger size of black spots on the first abdominal segment relative to those on the eighth when the line is absent (opposite pattern in S. cosmioides). The species rarely exhibits a black marking on top of the mesothoracic segment, which is almost always present in S. cosmioides.

Agricultural fields, particularly soybean, cotton, and vegetable crops; also found on various weeds in disturbed habitats. Larvae are typically found on the lower parts of leaves. In northern Florida, larvae occur only in summer months despite adults being present year-round.

Native range: North America (southern United States as far west as Kansas and New Mexico), through the Caribbean and Central America into South America (Brazil to Argentina). Introduced to West Africa: Nigeria and Cameroon. Present in Belgium (status doubtful) and Denmark.

Adults are on wing year-round in tropical and subtropical regions. In northern Florida, adults occur throughout the year (withstanding several days of freezing weather), while larvae are present only in summer months. Approximately four generations per year occur in Florida, with one generation lasting 30–40 days.

Highly polyphagous. Larvae feed on a wide range of vegetables (beet, cabbage, carrot, collard, cowpea, eggplant, okra, pepper, potato, sweet potato, tomato, watermelon), fruits (avocado, citrus), field crops (peanut, sunflower, velvet bean, tobacco, soybean), and various flowers. Preferred weed hosts include Amaranthus species and Phytolacca americana. Lima bean is a preferred host, possibly due to cyanogenic glycoside content. Grasses are rarely eaten.

• Solanum lycopersicum - feeds onheavy feeder on tomato in Florida
• Glycine max - feeds onmajor pest in Brazil and Argentina
• Gossypium - feeds onassociated with cotton-growing regions
• Amaranthus - preferred hostpreferred weed host
• Phytolacca americana - preferred hostpreferred weed host
• Phaseolus lunatus - preferred hostpreferred host, possibly due to cyanogenic glycosides

Complete metamorphosis with four stages: egg, larva, pupa, adult. Eggs are flattened spheres measuring approximately 0.45 mm diameter and 0.35 mm height, green initially turning tan with age, laid in clusters covered with scales from the female's body; duration 4–6 days. Larvae have six instars, duration 14–20 days; feed gregariously when young, becoming solitary as they mature. Pupae are mahogany brown, 16–18 mm long and 5–6 mm wide, formed in soil at 5–10 cm depth; duration 11–13 days. Sexual dimorphism occurs in pupae, with females larger due to an additional instar. Adult lifespan is positively correlated with pupal size in females but negatively in males. Total generation time approximately 30–40 days. Four generations estimated per year in Florida.

Young larvae feed gregariously, skeletonizing leaves. As they mature, larvae become solitary and nocturnal, hiding on lower leaf parts during the day. When food-stressed, larvae will eat apical portions of branches, bore into stem tissue, and attack tubers near the soil surface. Larvae readily bore into fruit, particularly tomatoes. Adults are nocturnal.

Larvae function as primary consumers and significant herbivores in agricultural ecosystems. The species serves as host for numerous parasitoid wasps (Campoletis flavicincta, Chelonus insularis, Cotesia marginiventris, Euplectrus platyhypenae, Meteorus autographae, Meteorus laphygmae, Ophion flavidus) and flies (Choeteprosopa hedemanni, Eucelatoria rubentis, Euphorocera claripennis, Gonia crassicornis, Lespensia sp., Winthemia quadripustulata, Winthemia rufopicta), contributing to food web complexity.

Major agricultural pest causing significant economic damage to soybean, cotton, and vegetable crops. In Brazil and Argentina, has emerged as one of the most important armyworm pests of soybean. In Florida, heavy feeder on tomatoes causing fruit damage. Subject of extensive research on alternative insecticides, particularly neem-based products containing azadirachtin, which reduce feeding and disrupt growth and development. Bt corn expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 proteins causes 100% mortality in larvae. Management relies primarily on foliar insecticides applied when larvae are small; botanical insecticides are generally ineffective.

• Spodoptera cosmioidesLarvae easily confused in South America; distinguished by presence of dark spot on mesothoracic segment (usually absent in S. eridania), continuous subspiracular line (interrupted in S. eridania), and smaller first abdominal segment spots relative to eighth when line absent (opposite in S. eridania)
• Spodoptera exiguaLarvae can be confused due to dark lateral spot; distinguished by position on mesothorax versus first abdominal segment in S. eridania
• Spodoptera frugiperdaSimilar distribution and pest status; distinguished by presence of four pinaculae per abdominal segment with Y-shaped head marking in S. frugiperda
• Spodoptera ornithogalliSimilar distribution; distinguished by paired black triangular spots with uninterrupted yellow stripes in S. ornithogalli

• agricultural pest
• armyworm
• defoliator
• soybean pest
• polyphagous
• neotropical
• introduced species
• Noctuidae
• Spodoptera
• integrated pest management
• Bt resistance
• neem insecticide

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Quick Guide to Armyworms on Soybean | Beetles In The Bush
• Noctuidae | Beetles In The Bush | Page 2
• October | 2013 | Beetles In The Bush
• Brazil | Beetles In The Bush
• Lepidoptera | Beetles In The Bush | Page 6
• Argentina | Beetles In The Bush | Page 2