IPMP3.0, Oregon State University, Copyright 2000





Sampling and Action Threshold

Development Model

Registered Insecticides


[Insect Management]


Mint Flea Beetle Adult

Mint flea beetles overwinter as eggs in the soil near the crown of mint plants. Eggs hatch early April through early May. Larvae feed initially on small mint roots and later tunnel into rhizomes. Larval development is completed during late May and early June. Pupation is in the soil near the rhizomes. The pupal stage is completed in about 3 to 4 weeks. Adults begin emerging from the soil during early July. Damage to mint foliage fed upon by adults is characteristic; the leaves appear riddled as if by shotgun pellets. Adult females usually delay depositing eggs for 2 to 3 weeks after emergence. Females have wings, but seldom disperse by flight. Males are incapable of flight. Therefore, dispersal is usually slow and occurs by hopping or walking. At harvest, adults disperse to adjacent fields or to margins of fields seeking uncut plants. Eggs may either be deposited in mint fields or along field margins. Egg laying continues into the fall until the onset of freezing temperatures. There is one complete generation each year. Planting from infested rootstock is one of the principal ways new mint flea beetle infestations are established.

The use of degree-days (DD), using a base temperature of 41F, accumulated from January 1, is an effective method of predicting the occurrence of different life stages of mint flea beetle in the field (Morris, 1990). The following degree-day requirements may be used to predict the presence of different stages of mint flea beetle in central Oregon:

Degree-day requirements for different stages of mint flea beetle:

1st instar larvae      405 DD
2nd instar larvae     575 DD
3rd instar larvae      775 DD
Prepupae                1045 DD
Pupae                      1370 DD
Adults                      1555 DD

Run the development model to determine development of mint flea beetle in your area.