Natural Connections: Further Observations Of Forked Fungus Beetles

Katherine Woolley is about to start her junior year as an environmental education major at Western Colorado University. This summer, as a Summer Naturalist Intern at the Museum, she taught our Junior Naturalist programs and showed a real talent for finding and appreciating the oddest parts of nature

I was dragging my feet on a sunny afternoon after a long day of sitting in front of my computer lesson planning and preparing supplies for my upcoming Junior Naturalist program I co-run with my fellow intern. I didn't really feel like going on a hike, but the urge to go see what my forked fungus beetles were up to ended up outweighing my desire to sit on the couch and never leave. Since my first sighting of them this summer, I've found plenty more shelf mushrooms that house beetles. Thanks to their stationary lifestyle, I have been able to get to know each pair quite well and identify their home polypore easily. Today, I was on my way to see my favorite male and his mate.

I spotted the male first. He was sitting on the highest point of the mushroom shelf like he was the king of the hill. Then I spotted his mate, who to my surprise, looked like she was sitting up. I knelt down and cocked my head to the side to get a better look. For beetles who usually crawl on all six legs, this was an unusual position. Was she laying eggs? I couldn't be quite sure.

I searched carefully for egg capsules in the spot where I first saw this beetle. Sure enough, there was a little line of eggs! Female forked fungus beetles lay 8 to 12 eggs on the surface of their polypore or just below the surface. Eggs are laid one at a time and then covered by a sticky black material created by the female. This material is placed to the side of each egg when it is first produced and then is spread over the egg using little hairs that grow on the underside of the female's abdomen.

Focusing my attention back on the female’s current location, I witnessed more of the egg laying process. By this time the beetle was up higher on the fungus and I was able to see her ovipositor at work. Her ovipositor was small, black and cone-shaped with the narrower part toward the bottom. What a treat to see! Then I got just a little too close to her and she retracted her ovipositor back into her abdomen.

I was so enraptured with watching the egg laying that I almost missed the process that occurs before eggs can even be laid. On the fungus shelf to my right, I saw another female with a male directly on top of her. In an instant I realized what was happening and my face grew red. After the initial shock of interrupting an intimate moment between fungus beetles, I started to giggle.

Like many other insects, the copulation process begins when the male climbs onto the back of the female. In the case of forked fungus beetles, the male climbs on so he is facing the opposite direction of the female. Then the male will use his legs to hold onto the female's wing coverings that are called elytra. Forked fungus beetles have proven to have phenomenal grip strength, and they most certainly need it. The two forked horns that adorn the males’ heads are not just for show, they are for prying other mating males off of females. If male fungus beetles want to pass on their genetic material, they have to be really good at holding on to avoid getting dislodged by a competing male.

After I snapped some pictures, I realized I was definitely interrupting and should probably back off. I checked on the female who was laying her eggs just a minute ago, but she was gone. I scolded myself for getting too excited about documenting what I was seeing and scaring her away during such an important moment. I whispered an apology to all the beetles who occupied both of the fungi and backed away, promising to give them some space for the next few days. As I walked home, I was so grateful I had chosen to go on a hike that day even when I really didn't want to. If I hadn't, I wouldn't have gotten to watch beetle life in the making. Yet again, I was shown that walks on the Forest Lodge Nature Trail are truly never boring.

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