Butterflies May Be A Nuisance; Still Need to Worry About Beetles

Thistle caterpillar

Anyone else's truck radiator completely covered in painted lady butterflies? These butterflies indicate the second generation of thistle caterpillars.

Perry News
Painted lady butterflies in your radiator? Source: Perry News

We are getting questions as to whether or not the third generation of these hungry-hungry caterpillars will be avoided with the insecticides sprayed with in-season fungicide. Only time will tell.  However, we typically do not see three flushes of these pests. If we do, will they cause the kind of damage that would warrant a treatment? Our team doubts it. 

After the past few weeks of scouting, we're seeing that the youngest beans were those that sustained the majority of the thistle caterpillar damage.  At this point in the season, the soybean crop should be far enough along to put up with a little bit of feeding and still not suffer yield loss. 

Japanese beetles should remain on your scouting radar.

While caterpillars may not be a current concern, we DO need to continue to scout for Japanese Beetles, grasshoppers, and aphids. Remember that in the R stages of beans 20% defoliation is the economic-threshold for loss. 

More questions about scouting for late-season pests? Give our agronomy team a call.