These moles can fly and swim!? (Mole Crickets)

This week we're digging into Mole Crickets! Their behaviors, tunnels, songs, and some cool cultural significance. 

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Transcript: 

 

Welcome back to episode 34 of insects for fun! I’m your host as always, Mitchel Logan and today we’re talking about Mole Crickets, but before we get into that I have a quick PSA. I got messaged through the fb account asking where people can send me questions or topics they would like to learn about, and the answer is my email which is insectsfordummies@gmail.com. I really do welcome requests, and of course listener stories if you have any! Now let’s get back to the program.

Mole crickets are in the family Gryllotalpidae and there are approximately 107 species known today, but I’m sure there are more. These crickets are found all over the world and they are all well equipped for life underground. As you might expect, Mole crickets got their name because they spend a good majority of their life in a series of burrows all made for various purposes. In fact they start digging as soon as they hatch from their eggs because this is where their lives start! They don’t just act like a mole though, they are also built like a mole too with very strong forearms that are shaped like the paws of a mole. This is a great example of a biological term known as convergent evolution which simply means species from different origins have evolved similar traits because of a shared environment. In this case that environment would be life underground and as it turns out, wide forearms with short appendages make for a great digging tool! 

 

They don’t have legs built for jumping so you won’t see them jump much if ever. Unlike more traditional crickets, they’re whole body is built for pushing and moving through dirt, but many of them can fly and even swim which is honestly quite shocking. 

 

Adult mole crickets are typically between 1 and 2 inches long or 3 and 5cm. They have cylindrical bodies with an armored head and thorax which probably act like a miners hard helmet. also have two sets of wings, the forewings which are what you see immediately and the hind wings which are underneath but often are much longer than the forewings. I’ve never actually seen one fly before but I guess it usually happens with females after sunset or very early in the morning. I have seen them do short hops outside of their burrows though. These crickets are attracted to lights so if you live in an area that has them you can find them near well lit areas. They’re also pretty buoyant because they have small hairs covering their body which traps air, and they use their shovel-like forearms to paddle water.

Earlier I briefly mentioned the tunnel systems these crickets live in, but now I’m going to actually dig into that information (badum chuck). Mole crickets make a variety of tunnels depending on what it is they are doing at the time. For example, when a mole cricket is foraging for food they often make tunnels close to the surface of the soil and in softer substrates like sandy soil, you can clearly see the elevated trails left by them. 

 

If the males are looking to attract a female then they make a very different kind of tunnel which actually acts as a horn to amplify their songs. The entrance is much wider than a normal one and it narrows into a chamber referred to as a “bulb”. It’s kind of shaped like a bulb which is I guess why they name it that, but the function is to act as an acoustic room which amplifies its sound. Mole crickets actually don’t face the opening of their tunnels while calling for a mate, and the innermost end of the bulb is typically just a wall of dirt. If there are any additions to the structure they branch off from the mid section of the bulb. 

 

At least from what we know based on the European Mole Crickets. Some mole crickets even make two openings that both lead to one tunnel which is commonly seen in Tawny Mole crickets and African Mole crickets.

 

The tunnels these mole crickets make for singing work so well that you can actually hear mole crickets from 600 meters away. Each species of mole cricket has its own chirp but they tend to be one pitch which is then modulated at different speeds. Many mole crickets keep their song around 3khz but have different speeds for which its oscillated. I’ll play you an example now. (insert mole cricket song) these crickets actually rival cicadas for how loud they are. In my episode on Cicadas we learned that those bugs can sing at 90 decibels and it turns out they are not the only ones. A research article published about noise mechanics stated that the loudest mole cricket song in their study was recorded at 92 decibels and that was from 1m away. That’s louder than a lawnmower. If you’re near one you can actually feel the ground vibrate because of how powerful the song is. In the popular series Animal Crossing you can find mole crickets by following the song. It’s quite loud and gets louder the closer you get to it, at which point you have to dig a hole to find it.

Now depending on your beliefs or even your profession the mole cricket will have various meanings from huge pain to delicacy or even a weather forecaster. 

 

People who work on golf courses or outdoor sports fields in turf management think of mole crickets as a bane to their existence due to the nature of herbivorous mole crickets feeding on the root systems of turf grass. It’s not just about killing the grass, but also making the turf less flat which causes performance issues, especially on golf courses. These damages are often caused by invasive mole crickets which have managed to get around the world with the help of ships. In Florida for example there are three different invasive mole crickets that are responsible for a lot of destruction on turf grass and even the yards of residents, and one of them, called the southern mole cricket, is actually carnivorous and makes burrows in the ground to find worms, grubs, and other small critters hiding in the dirt.

If you happen to be in Thailand, Vietnam or the Philippines then you might find mole crickets to be a great source of vitamins and protein. Mole crickets make for various meals in these countries from being shallow fried or baked to stir fried. In Pampanga Philippines, mole crickets are a staple, the same way cheese is popular in Wisconsin and are used in a variety of dishes including a crispy snack to pair with beer. In the Philippines it's known as kamaru so if you see anything with that name then it's sure to have mole crickets. If you’re curious about the health benefits etc one of my first episodes on this podcast was about entomophagy and I go into all the details. 

In Latin America, mole crickets are believed to be both a sign of good luck, and a weather forecaster. If you find one in your house it’s perceived as a good omen and if you see them making many tunnels you should expect rain in the near future. I personally don’t quite understand the rain one because mole crickets will be digging regardless of the weather but who knows! What I do know is that increased moisture in the soil causes increased surface tunneling as found in a study done by North Carolina Universities department of Entomology.