Corn Earworm Update

Summing Up! The corn we picked today had few earworms. It looks like there won't be much damage from earworms in the next corn patches that we will be picking the next several weeks.

This special issue of our newsletter was inspired by the first customer of the morning. She entered our stand with a big smile when she saw our corn bin.

My short conversation with the woman went something like this:

"Oh, the ears are bigger!" said the woman smiling and a bit surprised when she first saw the corn in the bin.

"Not only that," I replied, "but there are few earworms."

"Really!' she sounded almost shocked, " I thought they would be there for the duration!"

I paused a moment before I started explaining some of the things I knew about corn earworms. "They come in waves, " I explained.

"Where do they come from?" she asked.

"From night flying moths. They normally are able to overwinter only in the south but this year they must have overwintered right here in Michigan. That's why they were so early. Normally, they migrate north from the deep south (with the help of strong southerly breezes) and don't arrive here until late August." I then pointed out our earworm trap (a big white net gizmo in the cornfield you can see from the stand) and explained that the trap is baited with an earworm pheromone (sex attractant) and we monitor how bad the earworms will be by seeing how many moths we trap.

"We aren't trapping many at all, right now," I told her, "so we shouldn't have much earworm damage the next few weeks. She smiled and then quickly picked out her corn.

Some other notes about earworms. The moths fly at night to avoid the birds, which not only devour the flying moths but the worms, which are not worms at all but caterpillars. Corn earworm is a major problem in the south since they not only feed on corn but cotton. Another name for a corn earworm is a cotton bollworm. Normally in the north there is only a single generation (one wave), in the south (and perhaps this year in Michigan) there are more than two generations. Since earworm moths are attracted to field corn when it starts to make ears (TASSEL STAGE) a dilution takes place since suddenly there are so many darned places for the moths to lay their eggs. (they lay them on the corn's silk) that there is less chance that they will lay there eggs on the silk of a particular ear. In other words, there are many more ears of corn to choose from (both field and sweet) so it is less likely that any single ear is damaged.  

Tom