HPIPM:Mint Mint Stem Borer

Author: Sue Blodgett & Bill Grey

Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Hexapoda
Class	Insecta
Subclass	Pterygota
Infraclass	Neoptera
Order	Coleoptera
Suborder	Polyphaga
Infraorder	Cucujiformia
Superfamily	Chrysomeloidea
Family	Cerambycidae
Subfamily	Lamiinae
Tribe	Acanthocinini
Genus	Dectes

Scientific Name

Dectes texanus

Common Name

soybean stem borer

Mint Stem Borer is a minor pest of mint in Montana and rarely has warranted treatment.

Identification (life cycle and seasonal history)

Mint stem borer is a black weevil, about 1/8 inch long, that overwinters in hollow mint stems or soil debris, becoming active in early summer. The female chews a hole in a mint stem near the soil line and deposits a single egg in the stem. Larvae hatch and begin feeding within the stem and into the rhizomes, feeding for a 3 –4 week period. The insect pupates within the stem, emerging as an adult about 2 weeks later. There may be a partial second generation in late fields. The mint stem borer feeds on peppermint, native and scotch spearmint, wild mints, goldenrod and Kochia.

Plant response and damage

Affected stems appear weakened near the soil surface where the eggs are laid and the larvae are feeding. Infested plants generally appear weak with the early visible symptoms of yellowing, wilting, and lodging. Damage from the mint stem borer is greatest in stressed plants and in older stands.

Management approaches

Adults can be sampled using a sweep net or wooden stake coated with stickum in early summer. Larvae are sampled by collecting, splitting, and examining mint stems for the presence of larva or feeding damage.

Cultural Control

The best method for mint stem borer control is to select clean, certified rootstock free of diseases and pests. Since the mint stem borer may increase in weeds such as wild mints, goldenrod and Kochia, weed control adjacent to mint production can reduce alternate habitats for this pest.

Chemical Control

No insecticides are registered to control mint stem borer. However, treatments applied for loopers or aphids applied during May to early June generally reduce populations Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.