Stalk Borer
From Bugwoodwiki
|
Contents |
Importance
The stalk borer is widely distributed throughout the Eastern United States and Canada. It attacks over 175 herbaceous and woody plant species. Corn, grasses, and giant ragweed are favored hosts. However, succulent sycamore shoots are killed occasionally in nurseries and young plantations.
Identifying the Insect (fig. 14a)
Larvae have broad stripes of pale white and brown interrupted by a distinct band of purplish brown around the third thoracic and first abdominal segments. Mature larvae are 25 to 32 mm long. Adults are robust moths; their forewings are purplish brown with several small white spots. Eggs are globular and whitish brown.
|
| Figure 14a. - Stalk borer adult |
Identifying the Injury (fig. 14c)
Sudden wilting and flagging of succulent shoots with 3-mm-diameter round entrance holes occur in late spring. Excrement pellets often are present at entrance holes. Opening the shoot will reveal a tunnel and larva.
|
| Figure 14c. - Terminal being killed by larval tunneling, gallery entrance near apex. |
Biology
Overwintering eggs hatch from April to June. Young larvae feed on grasses; older larvae seek larger, succulent stems and often migrate from herbaceous plants to young sycamore trees. Larval development varies from 60 to 130 days. Mature larvae abandon their hosts and pupate just below the soil surface. Moths emerge from August to October and deposit up to 2,000 eggs each on grasses where they overwinter. There is one generation per year.
Control
Damage can be minimized by disking weedy borders of nurseries and young plantations to destroy breeding sites in early August. Direct controls may be needed.
References
Leininger, T.D; Solomon, J.D.; Wilson, A. Dan; Schiff, N.M. 1999. A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury of Sycamore. Gen. Tech. Rep. SRS-28. Asheville, NC: USDA Forest Service, Southern Research Station. 44 p.
