Anomis erosa Hobner Lepidoptera Noctuidae

Natural History

Distribution. This species is found in South America, Africa, southern Asia, and Australia in addition to North America. It is generally considered to be a southeastern species, and indeed it is most common there. However, it has been reported from as far north as Massachusetts and Montreal, Canada, and as far west as Kansas and Texas. Its distribution also extends southward through Mexico and the Caribbean region.

Host Plants. Okra caterpillar feeds primarily on plants in the family Malvaceae. Okra is the only vegetable crop affected, but its caterpillar also feeds on such ornamental or weedy plants as rose-of-sharon, Hibiscus syriacus; swamp rose, Hibiscus moscheutos; cotton rose, Hibiscus mutilabilis; chinese mallow, Hibiscus sinensis; roselle, Hibiscus sabdariffa; flour-of-an-hour, Hibiscus trionum; velvet leaf, Abutilon theophrasti; flowering maple, Abutilon striatum; hollyhock, Althaea rosea; and round-leaved mallow, Malva rotundifolia. It also can be found on cotton, and though it is not generally thought to be a common pest of this crop, it very closely resembles cotton leafworm, Alabama argillacea (Hubner), so it may be misidentified and its abundance underestimated (Creighton, 1936). Okra caterpillar is also reported to feed on Peperomia sp., family Piperaceae.

Natural Enemies. The natural enemies of okra caterpillar are mostly generalists that attack other caterpillars. For example, paper wasps, Polistes spp. (Hymenoptera: Vespidae) are commonly feed on larvae, as do ground beetles (Coleoptera: Carabidae), stink bugs (Hemiptera: Pentatomidae), and assassin bugs (Hemiptera: Reduviidae). Parasitoids of okra caterpillar include Trichogramma sp. (Hymenoptera: Trichogrammatidae), Apanteles bedelliae Viereck

(Hymenoptera: Braconidae), Itoplectis conquisitor (Say) (Hymenoptera: Ichneumonidae), Copidosoma truncatel-lum (Dalman) (Hymenoptera: Encyrtidae), Syntomo-sphyrum esurus (Riley) (Hymenoptera: Eulophidae), and Eusisyropa blanda (Osten Sacken) Diptera: Tachini-dae). Creighton (1936) indicated that S. esurus was the most important parasitoid in his studies conducted in Florida.

Life Cycle and Description. The life cycle of this insect is poorly documented but has been observed in the field from March-October in northern Florida and throughout the year in southern Florida. As a life cycle can be completed in about 35 days, several generations are possible annually. It is thought to overwinter in the pupal stage, but this is not satisfactorily proven.

  1. The egg is basically spherical, but flattened at the point of attachment. It measures about 0.8 mm in diameter, and bears 31-38 ribs, but most ribs fade before reaching the apex of the egg. Initially whitish, the egg soon turns greenish. They are deposited singly on foliage. Duration of the egg stage is about four days (range 3-6 days).
  2. The larva is reported to display 5-7 instars. Mean duration of the larval stage is about 16 days (range 13-22 days). It grows from about 2 mm long at hatching to about 35 mm long at maturity. The larva feeds during daylight hours, moves with a typical looper-like gait, and frequents the underside of the leaves. The larva is yellowish-green or green, with a dark stripe dorsally, though it acquires white dorsolat-eral stripes along the length of its body. As the larva matures, an irregular and broad yellow stripe develops laterally above the spiracles. There are four pairs of prolegs, three abdominal plus the anal prolegs, present on the large larvae. The first pair of abdominal prolegs is reduced in size, relative to the other pairs. About two days before termination of the larval stage the larva folds a section of leaf and anchors it with silk; this is the site of pupation. (See color figure 54.)
  3. Initially, the pupa is bright green, but soon turns brown and eventually almost black. It measures about 15 mm long. The tip of the abdomen possesses

Okra caterpillar larva.

Adult okra caterpillar.

short bristles and hooks which anchor the pupal case to silk webbing. Duration of the pupal stage is about 12 days (range 8-15 days).

Adult. The body of the adult is yellowish or rust. The forewing is marked with irregular yellowish, rust, and gray areas, though the hind wings are brownish, and darker distally. Adults commence oviposition about five days after emergence, and may continue egg production for 25 days. Adults are nocturnal.

The biology of okra caterpillar was described by Chittenden (1913b), Dozier (1917), and Creighton (1936). The larva was included in the key by Crumb (1956). (See color figure 245.)

Damage

The larvae eat large irregular hole in the leaves of okra, sometimes defoliating entire plants. It is not a common pest, even in the deep south, where it is most abundant.

Management

This caterpillar rarely is abundant enough to warrant suppression, but insecticides applied to the foliage are effective, especially if applied when the larvae are young.

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