This Week’s Creature Feature: The Fiery Searcher Caterpillar Hunter
At North Point State Park looking for little blue herons, I was distracted by a female cardinal looking for insects in a nearby tree. Cardinals are generally seed-eaters but tend to look for insects when they have nestlings, so I thought she might lead me to her nest. Instead, when she was about 10 feet away, she grabbed a bright green beetle but immediately dropped it.
As the beetle landed on the ground at my feet, she headed down to get it but stopped when she saw me. I had to see what she was after. What I found was one of the most brilliantly colored creatures I have ever seen. After crawling around on the ground trying to get a photo of the rapidly running bug (and having two park rangers stopping to ask what I was doing), I went home and did a little research.
The beetle, no kidding, is called the fiery searcher caterpillar hunter, scientific name: Calosoma scrutator. Its entire existence is based on finding and eating caterpillars. After hatching, they enter a series of three larval forms, called instars, before they eventually become a hard-shelled beetle. Each of the larval instars feed on underground caterpillars known as cutworms.
After about a month, when they have had their fill of cutworms, they change into a dormant pupal form, then emerge as a brilliant green-red-purple caterpillar hunter. As adults, the quarter-sized beetles can fly and climb trees. They now switch food preferences and frequently seek out tent caterpillars.
These beetles are unusual because they can live up to five years as adults and have five breeding seasons. If you were to try to pick one up, it might spray a foul-smelling liquid on you, and it might bite.
The caterpillar hunters help control gypsy moths as well as tent caterpillars. They are thought to be common but are killed by yard and farm peticides like grub poisons and by spraying yards for mosquitoes. So you might think twice about who you want to kill.