Coexisting with corn earworms

Jun. 15, 2013 @ 11:23 PM

During the many years I've been involved with farmers’ markets, I've noticed a very interesting phenomenon. Lots of people who shop at farmers’ markets are interested in purchasing organic or sustainable or no-spray vegetables and fruits, but the idea of bugs crawling on their food is too much to handle.  On farms, farmers, crops and bugs live together – not necessarily live in harmony, but they co-exist.

The bugs that live on farms can generally be classified into two categories: Pests, the bad bugs. And beneficial insects, the good bugs. The pests do damage to crops. These bugs tend to be the herbivores. They chew holes in fruits and vegetables and eat leaves of plants, which makes photosynthesis and growth more difficult. Some even chew on roots and stems, causing the whole plant to die. The beneficial insects are the predators. They eat the pests and do other work, including pollination, while leaving the plants and vegetables alone. Some farmers go to great lengths to attract beneficial insects to their farms.

Bug hierarchy can be compared to the hierarchy in the animal kingdom. Pests are similar to rabbits or deer -- there are lots of them and they reproduce quickly! The beneficial insects are similar to predators, such as wolves or foxes or bears and their populations tend to be smaller. When there is a good balance of pests and beneficial insects on a farm, the beneficial population keeps the pest population in check.

A good balance can be hard to strike and can take years of hard work. Factors that are beyond a farmer’s control can upset the balance very quickly. Often, no matter how hard farmers try to attract beneficial insects to their farms, the population of pests is bigger and more voracious than beneficial insects can control. So, farmers sometimes have to resort to other measures of pest control. Those measures can include picking off the pests by hand, using organic sprays to keep the pests off the crops or using chemical pesticides to kill the pests before they do too much damage. However, chemical pesticides can also kill off populations of beneficial insects.

So, why does the first corn of the season lead me to a long discourse on insects? It is all because of corn earworms, the pesky, little worms that like to chew on the tip of an ear of corn. These little worms are difficult to control. The good thing is, they don't damage the whole ear of corn -- usually they just chew on the end of it. There are lots of farmers who sell corn at local farmers’ markets who won’t spray their corn and have learned to co-exist with the worms. Often, they encourage their customers to cut off the ends of the cob that has been chewed on by the worms. As a farmer once said to me, “If it’s good enough and safe enough for the worms to eat, it is good enough for me!”

Erin Kauffman is market manager of the Durham Farmers' Market.