Ostrinia nubilalis

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Authors: Dr. Alton “Stormy” Sparks, Jr. and Dr. David G. Riley - University of Georgia

3067079
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Hexapoda (including Insecta)
Order: Lepidoptera
Family: Crambidae
Genus: Ostrinia
Species: O. nubilalis
Scientific Name
Ostrinia nubilalis
(Hubner)
Common Names

European corn borer

Contents

Description

Adult

The moths are fairly small, with males having a wingspan of 20-26 mm and females 25-34 mm. Adults caught in south Georgia are generally smaller than the 'typical' European corn borer from the mid-west corn belt. Females are pale-yellow to light brown, with darker zig-zag lines across the forewing and hind wing. Males are darker, usually pale brown, with dark zig-zag lines across the forewing and hind wing. Both sexes also have yellowish to gold colored patches on the wings, which are more apparent against the darker background in the male.

Immature stages

Eggs are oval, flattened and creamy white when first laid and darken with age. They are deposited in small clusters with the eggs overlapped like fish scales. Larvae tend to be light brown or pinkish-gray, with a brown to black head capsule. Full grown larvae are about 2 cm in length. The body is marked with darker circles on each segment along the midline of the back. Larvae are frequently referred to has having a 'greasy' look. Larvae can be easily confused with other borers present in plant stalks.

Biology

Life cycle

Eggs are generally deposited in irregular clusters of about 15 to 20 on the underside of leaves and hatch in 4 to 9 days depending on the temperature. Larvae usually develop through 5 or 6 instars with a development period of over 30 days and a pupal stage of about 12 days. There are probably 3 or 4 generations in Georgia.

Seasonal distribution

European corn borer overwinters in the larval stage, with pupation and emergence of adults in early spring. Populations in Georgia generally do not reach very high levels, but are of concern in sweet corn, peppers and snap beans because of shipping restrictions associated with the presence of this pest.

Damage to Crop

European corn borer is considered to be the most important sweet corn pest in northern production regions. In Georgia, this pest is usually controlled by insecticide applications targeted at corn earworm. ECB can attack all above ground parts of a corn plant, including the leaves, stalk, tassels, silk, kernels, and cob. Older larvae tend to bore into the stalk, base of the ear, cob, or kernels. Larvae damage both the stem and fruit of beans and pepper. In Georgia, level of damage from ECB in vegetables is usually minimal, but the presence of this pest in these crops restricts shipment to some states. Trapping and treatment programs allow for shipment of these crops to California and Texas. For regulations associated with shipment of these crops to California or Texas, contact the Georgia Department of Agriculture.

Management

In Georgia, European corn borer is generally controlled by insecticide applications targeting other pests. The regulatory programs for sweet corn, pepper, and snap bean require monitoring of ECB with pheromone traps, insecticide applications, and phyto-sanitary certificates, depending on the crop involved and the state to which the produce will be shipped. For regulations associated with shipment of these crops to California or Texas, contact the Georgia Department of Agriculture.

Originally compiled from


Hosts

Sycamore, polar, yellow-poplar, peach, apple, pear. This polyphagous species feeds on plants representing 131 genera of 40 families including grains, grasses, weeds, herbaceous plants, flowers, and trees (Hodgson 1928). Corn is the preferred nonwoody plant. Trees are attacked only occasionally unless growing near heavily infested preferred hosts (Anonymous 1979, Tedders and others 1981).

Range

Introduced into the United States during the early 1900's and spread throughout the corn-growing areas east of the Rocky Mountains (Baerg 1951).

Description

Adult

Brownish moth with 24- to 29-mm wingspan (Vinal and Caffrey 1919). Forewings yellowish and brown with some streaking, banding, and spotting; hindwings grayish brown (Vinal and Caffrey 1919). Head covered with light yellowish brown scales. Dorsum of thorax cinnamon brown in males and light yellowish brown in females.

Egg

Circular to oval and slightly convex on upper surface, averaging 0.97 mm long and 0.74 mm wide. Egg surface sculptured with shallow pentagonal pits. When first deposited, eggs opaque to iridescent white and within 2 days assume yellowish tinge (Vinal and Caffrey 1919).

Larva

Measures about 25 mm long with head capsule width of about 2.2 mm when mature. Head and thoracic shields shiny brown and mottled with black. Dirty white to pink body, gray or light brown with narrow, dark brown median line on dorsum; broad, pale brown to pink subdorsal line; and narrow, pale brown lateral line. Freshly abdominal prolegs bear almost complete circle of crochets (Peterson 1962, Vinal and Caffrey 1919).

Pupa

Light to dark brown and about 14 to 17 mm long. Tenth abdominal segment extended to form dark brown to black cremaster bearing eight long, hooked spines.

Biology

This borer overwinters within tunnels in its host as mature larvae, which pupate in May and emerge as adults during June in Illinois. Females deposit 500 to 600 eggs on leaves of host plants; egg incubation is about 1 week. In herbaceous hosts, young larvae feed on tassels and leaf sheaths and later burrow in stems and fruits. Development of first generation is completed in July; most moths emerge during August. Larvae of the second generation feed on, or within, hosts until the advent of severe winter weather. Larval feeding is resumed during spring. This borer has one or two generations per year (Baerg 1951, Vinal and Caffrey 1919).

Injury and Damage

On tree seedlings, the first sign of infestation is rapid wilting and dying of foliage, terminal leaders, and lateral branch tips, which at first may appear to be caused by a leaf disease. Closer inspection reveals large holes, up to 6.5 mm in diameter, in stems just above the lateral leaf axils, or occasionally just below the leaf axils. Noticeable quantities of large granular frass and excrement accumulate near entrances. The larval tunnel, kept relatively free of frass, extends in the pith from the entrance hole almost to the terminal bud and may extend several centimeters below the entrance hole.* On peach seedlings, injury can range from 2-mm-diameter holes in the bark to injuries that cause 10-mm-diameter limbs to break under their own weight. A conspicuous gummy exudate mixed with frass accumulates at larval feeding sites (Tedders and others 1981). In northern Italy, it causes considerable injury in tree nurseries by boring into succulent stems and lateral shoots of poplar seedlings, particularly clones that have strongly developed medullary tissue like that in eastern cottonwood (Anonymous 1979). About 90% of the limbs on 1- and 2-year-old trees in a Georgia peach orchard were damaged by larvae that had migrated late in the season from browntop millet that had been interplanted among the trees (Tedder and others 1981). In a similar case, 30% of the terminal shoots of 1-year-old sycamore nursery stock, and some yellow-poplar seedlings, were tunneled by larvae in an Indiana nursery.* In every recorded instance of significant damage to tree seedlings, more preferred hosts such as corn, cover crops, or weeds, either grew nearby or were interplanted with the trees. In such cases, the trees were attacked in late summer by larvae that had migrated from the herbaceous plants.

Control

Numerous parasites have been recorded (Arnaud 1978, Krombein and others 1979). Several insect parasites have been introduced from Europe to control the borer, and appreciable results have been obtained in some areas. Populations are adversely affected by dry summers and cold winters. Crows and other birds are effective larval predators (Baerg 1951). Despite many natural enemies of this borer, populations have to be controlled by insecticides, cultural methods, and planting resistant plant varieties. Cultural controls include plowing under infested herbaceous host plants and shredding or storing hosts in silos to destroy hibernating larvae. Several insecticides are registered for control and are effective when properly timed and applied.

  • Marshall, P.T. August 31, 1978. (personal communication). Indiana Department of Natural Resources, Vallonia, IN.

Gallery

3067080
Photo by James Solomon, USDA Forest Service, Bugwood.org

View in Bugwood Image Database
1857029
Photo by Ronald Smith, Auburn University, Bugwood.org

View in Bugwood Image Database

References

Solomon, J.D. 1995. Guide to insect borers of North American broadleaf trees and shrubs. Argic. Handbk. 706. Washington, DC: U.S. Department of Agriculture, Forest Service. 735 p.

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