INFO-BUG

Crop Selected: Alfalfa
Crop Development: Second cutting (early summer)
Pest Selected: Alfalfa Blotch Leafminer (ABL) Agromyza frontella

Biology

The alfalfa blotch leafminer (ABL) is a very small fly of which the larvae make blotch mines in alfalfa leaflets. In severe cases, blotch mines may be found on 50% or more of foliar leaflets.

ABL is a new pest in Ohio and is currently moving across the state from the northeast.

As ABL moves into an area, it may cause high levels of infestation initially. However, as beneficial parasites become established, the level of infestation declines significantly.

Click here to see

Alfalfa blotch leafminer damage to alfalfa

Assessment

Most research on blotch leafminer damage to alfalfa has shown that the loss in yield and hay quality is not sufficient to justify use of insecticides to control the leafminer.

Furthermore, due to overlapping generations and the internal nature of the infestation, control of this pest is difficult to achieve.

Estimates of infestation needed to warrant corrective action range from 30 to 60% of leaflets mined. Such infestations occur only during the initial period of establishment. Thus, chemical controls are not recommended.

Control

Beneficial parasites (little wasps) have been released in areas where the blotch leafminer has become established. Within a year or two the parasites become established and maintain the leafminer to insignificant levels of infestation.

Although, rescue treatment is not recommended for control of the blotch leafminer, the impact of infestation may be considered as a factor in deciding when treatment is required for the potato leafhopper, which is a more significant problem.

| Return to Ohio IPM Home Page. |