|Mint stem borer is a pest on mint in
Idaho and eastern Oregon. Adults are black, about 1/8 inch long. Larvae are pale
green to cream colored. Adults overwinter inside hollow stems or in soil debris in mint
fields. Adults become active in mid-May and early June. Mated females chew a hole in a
mint stem near the soil line and deposit a single egg in the wound. Larvae hatch in late
June and begin feeding on the tissues in the center of the stems and usually borrow into
the rhizomes. Larvae feed for 3 to 4 weeks until late July, then pupate. Generally, adults
emerge about 2 weeks later. However, some larvae have been found in mint stems as late as
October. There is one generation each year.
|Mint Stem Borer Larva and
This section contains information on identification of mint
stem borer in peppermint. See Baird et al. (1990) for
specific information on identifcation and biology of this pest. Mint stem borer
damage is confined to production areas in Idaho and Malheur County in Eastern Oregon.