European corn borer
Beginner
Scientific Name
Ostrinia nubilalis
Identification
Life stages: eggs, larvae, pupae, adult moths.
European corn borer (ECB) egg masses are creamy white and flattened. They are laid in clusters of 15-40. Each egg is slightly overlapped, giving the egg mass the appearance of fish scales. As hatch approaches, the dark black heads of the larvae become visible at the centre of each egg.
Larvae, 1.5–1.8 cm long, are easily identified by their dark heads and the paired dark spots running the length of the backs of their bodies. Newly hatched larvae are approximately 3 mm long. Fifth instar larvae reach 2.5 cm in length. The abdominal spots are not always present, especially on the younger instars.
Adult female moths are 2–2.5 cm long and yellowish brown with dark irregular bands running in wavy lines across the wings. Adult male moths are smaller and darker in colour than females.
Often Confused With
Cutworms
Stem
borer
Period of Activity
Borer development and population peaks can be predicted using accumulated growing degree-days(GDD) with a base temperature of 10°C.
- Determine the mean daily temperature.
- Subtract the base temperature from the mean temperature to give a daily GDD. If the resultant GDD is negative, count it as zero.
- Each daily GDD is then added up (accumulated) over the growing season.
Daily Max |
+ |
Daily Min |
- |
Base |
= |
GDD |
|
2 |
|
|
|
|
|
GDD Accumulations |
|||
Event |
Univoltine areas |
Bivoltine areas (Kent, Essex and parts of Elgin counties)* |
|
1st generation |
2nd generation |
||
First catch |
300 |
150 |
700 |
Peak catch |
650-700 |
300-350 |
1050-1100 |
*An overlap band exists between Sarnia and Niagara where both univoltine and bivoltine strains are present. These areas will experience a prolonged peak in activity lasting from early July through mid-August. Affected areas include Lambton, Middlesex, Oxford, Brant, Haldimand, Norfolk, Hamilton-Wentworth and Niagara. Univoltine and bivoltine moths emerge at different times.
In the bivoltine area, the first generation adults emerge in mid-June, and the population peaks in mid-July. Second generation populations peak in mid-August. In the univoltine areas corn borers usually emerge in late June or early July. Populations peak in late July to early August. Overlap areas experience a sustained peak flight for much of July and August.
Scouting Notes
Check wilted plants carefully. Look for holes on stems made by the larva to penetrate stems.
Thresholds
Not established. It is a sporadic pest in Ontario.
Advanced
Scientific Name
Ostrinia nubilalis
Identification
Life stages: eggs, larvae, pupae, adult moths.
European corn borer (ECB) egg masses are creamy white and flattened. They are laid in clusters of 15-40. Each egg is slightly overlapped, giving the egg mass the appearance of fish scales. As hatch approaches, the dark black heads of the larvae become visible at the centre of each egg.
Larvae, 1.5–1.8 cm long, are easily identified by their dark heads and the paired dark spots running the length of the backs of their bodies. Newly hatched larvae are approximately 3 mm long. Fifth instar larvae reach 2.5 cm in length. The abdominal spots are not always present, especially on the younger instars.
Adult female moths are 2–2.5 cm long and yellowish brown with dark irregular bands running in wavy lines across the wings. Adult male moths are smaller and darker in colour than females.
Often Confused With
Cutworms
Stem
borer
Biology
The European corn borer is a sporadic pest of potatoes, usually attacking the crop in cool seasons when corn development is delayed. Female moths lay egg masses on the underside of the leaves of potato plants. Larvae emerge after 3–9 days, depending on temperature. They feed on the leaves for a few days and then bore into the stem of the plant, destroying the pith and the vascular tissue. Larvae complete their development in the stem. Damaged stems wilt and then collapse. Fully grown larvae overwinter in stems left in the field after harvest. In the spring, larvae pupate and later emerge as adults.
Period of Activity
Borer development and population peaks can be predicted using accumulated growing degree-days(GDD) with a base temperature of 10°C.
- Determine the mean daily temperature.
- Subtract the base temperature from the mean temperature to give a daily GDD. If the resultant GDD is negative, count it as zero.
- Each daily GDD is then added up (accumulated) over the growing season.
Daily Max |
+ |
Daily Min |
- |
Base |
= |
GDD |
|
2 |
|
|
|
|
|
GDD Accumulations |
|||
Event |
Univoltine areas |
Bivoltine areas (Kent, Essex and parts of Elgin counties)* |
|
1st generation |
2nd generation |
||
First catch |
300 |
150 |
700 |
Peak catch |
650-700 |
300-350 |
1050-1100 |
*An overlap band exists between Sarnia and Niagara where both univoltine and bivoltine strains are present. These areas will experience a prolonged peak in activity lasting from early July through mid-August. Affected areas include Lambton, Middlesex, Oxford, Brant, Haldimand, Norfolk, Hamilton-Wentworth and Niagara. Univoltine and bivoltine moths emerge at different times.
In the bivoltine area, the first generation adults emerge in mid-June, and the population peaks in mid-July. Second generation populations peak in mid-August. In the univoltine areas corn borers usually emerge in late June or early July. Populations peak in late July to early August. Overlap areas experience a sustained peak flight for much of July and August.
Scouting Notes
Check wilted plants carefully. Look for holes on stems made by the larva to penetrate stems.
Thresholds
Not established. It is a sporadic pest in Ontario.
Management Notes
Populations are usually very low. No chemical control is required.
