I am back from the first reconnaissance trip to the Cheringoma Plateau in the eastern part of Gorongosa. It was slow going and in nearly all places we were forced to do a lot of road clearing, removing or finding a way around fallen trees, but the rewards were great. The eastern part of the park is one of the most gorgeous areas I have ever been to, full of deep gorges and canyons, waterfalls, and beautiful forests. During this trip I did not have much time to look for insects, hardly any in fact, but one species was rather difficult not to notice.
We spent the last night of the recon in a remote outpost of park rangers, a place that happened to sit on top of deep, sandy soils. And such soils are just what the Tobacco crickets (Brachytrupes membranaceus) love, and they make it loud and clear. At around 7:30 pm, just after it got really dark, the entire camp suddenly erupted in incredibly loud, buzzing racket when about a dozen cricket males started singing at the entrances to their burrows. They were very easy to locate, but getting too close to one was painful. Listening to a singing Tobacco cricket from a distance of a meter or less is akin to staring into a bright lightbulb – for a while, once you turn your eyes away, you still see the light and not much more, and the cricket’s song leaves your hearing similarly dulled and almost unable to perceive any other sounds for a few seconds.
This of course is not surprising, considering that this species is the size of a small mouse. Tobacco crickets are giants, reputedly the largest species of crickets in the world (but there are several related species in Asia, which are similarly huge). They also appear to be the loudest. I recorded one of the males and you can listen to it here: to get the most life-like impression of this sound, crank up the volume of your computer to its maximum setting and place your ear near the speaker.
Tobacco crickets get their name from their preference for young tobacco plants, and in some areas of Africa they are considered pests. Unlike most crickets and other orthopterans, these insects gather and store food in their burrows, and are able to preserve it so that mold does not destroy it. They are also unusual in a well-developed maternal care. The female, which has a strongly reduced ovipositor, lays the eggs in her burrow and cares for them and the newly hatched nymphs until they are ready to forage on their own. All in all fascinating creatures, which also taught me to look for large holes in the ground before setting up a tent, and move as far away from them as possible.
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Fascinating! I ran the audio recording through a spectrogram software to determine the frequency of the cricket. Its rather interesting… at a high frequency resolution there seems to be very distinct and constant frequencies from 4440 to 5129 Hz in approximately 100 Hz steps. Is this a recording artifact or something inherent in the cricket’s method of sound creation? Do you know any references detailing an acoustic analysis of this cricket?
I love your blog Piotr and really look forward to it arriving in my in box. These tobacco crickets, are those their wings at all or just for sound?