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Agronomic Crops Network

Ohio State University Extension


Pests to watch: Black cutworm, slugs, alfalfa weevil and cereal leaf beetle

Slug feeding on soybean seedling.

As we start to dry out in some parts of the state and come out of this cold spell, there will be insects and other pests out an about that will be hungry:

Black cutworm:  Purdue University has reported a record flight of black cutworm (  Any corn that is emerging or has come up should be scouted for the presence of cutworm activity. For management, see our fact sheet at

Slugs: We are likely entering that period of heavy slug feeding, so, just like cutworm, any corn or soybean that is emerging will need to be inspected for slugs, especially in fields with a history of slug damage (see figure, photo credit S. Stitzlein).  The two available baits are those containing metaldehyde (Deadline MPs and others), and those with iron phosphate (Sluggo).  See our slug fact sheet for more information: . 

Alfalfa Weevil:  We have seen a fair amount of feeding of alfalfa weevil across the state.  Some of these fields are approaching threshold, but they are also approaching the early cutting stage.  Alfalfa 12 inches long with > 2 weevils per plant or 16 inches >4 weevils could be harvested early to avoid further damage.

Cereal leaf beetle: While walking through a few wheat fields last week I noticed adult cereal leaf beetles as well as a few eggs.  Both adults and larvae cause defoliation, although larvae are the most damaging stage.  Heavily infested fields have frosty appearance due to the type of feeding.  Wheat fields should be scouted for the presence of larvae, which are small, black, and resemble bird droppings.  Wheat with an average of 2 or more cereal leaf beetle larvae per stem may need a treatment to prevent yield loss. 

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.