Cordyceps Fungus and butterflies/moths

Sometimes we spot something so weird or unusual that we just can’t stand it. We simply have to find out what it is and what happened.

Before I tell my story, let me introduce you to this fungus, one that infects moths and other insects. Cordyceps fungi that infect adult moths often causes them to go to a high place before they die. This ensures that when the fungal spores are released, they will spread over a larger area than if they died low or on the ground. Those we’ve found have been between 3 and 4 feet off the ground, attached to a plant. They are easier to spot in the winter, when most of the leaves have fallen. Fungi that infect caterpillars often causes them to go low, the fungi staying in the ground.

A fungus killed this moth

I well remember the time that I spotted a moth like this one. I can still picture the willow tree it was on, a short tree, as I was out walking with my camera. First, what was it to begin with? It had a vague moth shape and I had a sneaking suspicion that it was one. dead and growing fungus on it for some reason. I took photos of it but couldn’t find an answer to my questions. (This was before I joined Facebook, back in about 2003. If I had found it now, I could have found instantly what it was by posting photos on Facebook in the appropriate groups.) As I sat in the airport, waiting for a flight to a conference about butterflies, I deleted the photos. After all, I had only limited space on my laptop and I didn’t know what they were, after all.

At the conference, photos were shown of moths that were much like the one I had found. I realized that I had not only deleted the photos, but I had emptied my recycle bin. As I realized that, I also remembered that I hadn’t uploaded those images to my pc at home. They were gone for good. I was devastated.

Later I began to find more of these moths, of various species. The latest one was from January of 2022, on a walk in the woods. It was a larger moth than those I’ve spotted in the past. Its wings are quite tattered.

Found about 3 feet off the ground, a Cordyceps infected moth is attached to a branch of a Deerberry shrub.

So what is Cordyceps fungus? There are hundreds of species. Different species infect different insects and in different stages of their life cycle. Some species of the fungi infect the adult stage of the host species while others infect the larval stage of the host species.

One species is highly valued in Chinese herbal medicine. It grows in ghost moths in high grasslands. People will pay up to $18,000 for a kilogram or so of Ophiocordyceps sinensis. Their sale is regulated by the Chinese government. It has played a role in the Nepalese Civil War, due to its high value. In the summer, this particular fungus will infect caterpillars of a particular species. These caterpillars feed on plant roots about six inches underground. While they are underground, they are infected with the fungus, usually right after they molt when their cuticle is soft. The fungus grows in their bodies in the fall and winter. In the spring, when the snow melts, the fungus causes the weak and nearly-dead host caterpillars toward the surface of the soil. It then grows a spore filled stalk, dark brown, through their heads. This fungus infects through spores in the soil, so caterpillars do not crawl high before dying. In Tibet, the fungus name, translated to English, is ‘winter worm, summer grass’:  yartsa gunbu. In English, we call it ‘caterpillar fungus’.

People are fascinated with Cordyceps fungi. In the video games, THE LAST OF US, a mutated form of the fungus infects humans and causes the collapse of civilization.. In the book and subsequent movie, THE GIRL WITH ALL THE GIFTS, a mutation also infects humans and causes the collapse of civilization.

An internet search of images of Cordyceps fungus brings up a nightmare of infected critters.

As you walk and enjoy nature, keep your eyes open for the odd and unusual. This world has more amazing things than most of us realize!