Last week between the rain showers I walked out into our wheat fields to see how the wheat was doing. As I looked around everywhere I turned I saw a ladybug. Every place I stopped I could count at least 4 ladybugs in a square yard. 4 ladybugs in a square yard works out to 20,000 ladybugs per acre. That’s a lot of ladybugs, but so what?
Ladybugs, despite their cute name and cute appearance are actually savage predators. They feast on aphids and also devour spider mites and feed on other insect’s eggs. Ladybugs are beneficial insects, they help control the bad insects that will damage the wheat.
Chemical companies encourage farmers to apply insecticides to kill the bad insects. Those companies tell us to apply an insecticide to the seeds we plant or to spray on the fields. It doesn’t cost much they say and it acts as an insurance policy against an insect outbreak.
But insecticides are non-selective. They indiscriminately kill every insect, beneficials like ladybugs and harmful insects alike. By eliminating the beneficials we leave our fields wide open to attack by harmful insects.
Several years ago we had black cutworms eating our soybeans as they emerged. We sprayed the field with an insecticide. It was very effective and wiped out the cutworms. The beans thrived. Then late in the summer we had an outbreak of spider mites in the same field. In killing the cutworms we’d also taken out the beneficial insects that would’ve controlled the spider mites. We had to spray again with a different insecticide to take care of the spider mites.
Two years ago I heard an entomologist named Jon Lundgren speak at the National No-Till Conference. He said instead of routinely applying insecticides we should try to improve the environment for the beneficial predator insects in our fields.
He suggested these steps to encourage beneficial insects:
– Apply insecticides only as a last resort. It can take years to rebuild the population of beneficial insects after an insecticide application.
– Till the soil as little as possible, tilling destroys the habitat for the beneficial insects
– Increase the diversity of plants through cover crops, rotating different crops, and allowing grassy strips to grow along the edges of fields.
Sometimes it is necessary to apply insecticides. Outbreaks of bad insects can destroy a field crop or a vegetable garden if you don’t take action. But routine application of insecticides often do more harm than good. It’s better to let the ladybugs do it for you.