Gorongosa: An Irruption of Metaxymecus

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A plastic bag full of Metaxymecus (plus a single Mesopsis laticornis) collected within a few minutes at the lights of Gorongosa’s restaurant. These were released after photography. 

While I was in Gorongosa National Park in July and August 2015, I was witness to a population boom of the beautiful grasshopper Metaxymecus gracilipes. They were the first grasshopper species I found there, and I found them commonly night and day throughout my trip. One warm night in particular was spectacular, with huge numbers of them showing up at the lights of the restaurant, Chikalango. This species is widespread across the African continent, and judging by all the specimens in the collection at the E.O. Wilson Lab and the Gorongosa material at the Harvard Museum of Natural History, it might appear that this is a common species. Indeed, it has been collected from sites all across the park. However, each and every one of those specimens was collected in 2012. Piotr tells me that they were extremely abundant that year, and he had not seen a single one since, until 2015. Apparently the species must be very seasonal, prone to large population booms in certain years and to be almost nonexistent in other years. 2012 and 2015 were clearly good years for this species. Who knows when the next good year will come about for Metaxymecus? We will have to wait and see.

Obviously there is a great deal to be learned about the biology of this species, but Metaxymecus is not unique in that regard, and every organism on earth has its secrets. This is one of many things I find fascinating about entomology, or any science: there are always new things to be discovered. Even common species have unsolved mysteries, and everyday phenomena leave unanswered questions. It is in our nature to puzzle out these mysteries, and the best part is that we’ll never run out of ideas to explore!

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Metaxymecus can be recognized by its extremely long hind femora, which are inflated in the basal half and strongly narrowed in the apical half. The hind tibiae and hind tarsi are also quite elongated.

 

Orocharis: Northbound Traveler

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The male Jumping bush cricket from Newton, MA, that started me on my journey of understanding this species. 

Most people living in the eastern United States have never seen or heard of Orocharis saltator, the Jumping bush cricket, but they have surely heard its song. Click here for a recording from SINA. For a 20 mm-long insect, this is a very loud, distinctive song that can be heard in many an urban setting. This seemingly dull brown cricket has fascinated me for several years now because of its enormous range expansion, only recently documented, and its ability to live in very close association with humans.

Orocharis is a member of a chiefly tropical subfamily (Eneopterinae) of crickets, only a few of which make it into the U.S. Most of those species are restricted to Florida and the southeast, with only O. saltator and Hapithus agitator, the restless bush cricket, coming any further north than Virginia. Restless bush crickets have been documented as far north as New Haven county, Connecticut, but they are apparently uncommon in the northern part of their range. Jumping bush crickets were, up until recently, thought to only come north to New Jersey. This has changed very rapidly, very recently.

My first experience with Orocharis came on October 7, 2012, in Newton Highlands, MA. While listening to Fall field crickets and Carolina ground crickets (two common species in the northeast) in a small city park, I became aware of an odd cricket call that was distinctly different from anything I’d heard before. I tracked the call across the park to a row of cedar trees next to a basketball court. There were only a few isolated individuals calling, and one in particular was very close, but I couldn’t find him after almost 20 minutes of searching. Finally in desperation I grabbed the lower branches of the tree he was in and shook, and immediately a small brown creature rocketed out of the tangle. Upon capture, I recognized him immediately as a male O. saltator based on the habitus and song, which immediately sparked the memory in my mind of hearing it on the Songs of Insects website. I remembered reading that this was a mostly southern species, and I became very curious as to whether this could be a significant record. However, when I returned home and did some additional research, I found that according to photo records on BugGuide, Jumping bush crickets have been in New York state since at least 2005, and in Massachusetts since at least 2007. There were several other photos of the species from Newton, so it seemed like there were established populations in that area of Massachusetts.

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Female Orocharis saltator (Braintree, MA).

A year later, in September 2013, I was in Braintree, MA, and here I noticed that Orocharis was a dominant part of the nighttime insect chorus. Hearing this traditionally southern species calling in unison with traditionally northern species of crickets was an interesting sensation. Although they tended to be in very thick, impenetrable brush, I managed to secure a few specimens.

The next, and arguably most interesting point in this story is woefully incomplete. I was in Portsmouth, New Hampshire, on October 14, 2014, when I suddenly heard, incongruously, the unmistakable cry of Orocharis in a parking lot! There were a few individuals calling from three isolated trees surrounded by buildings. Unfortunately, they were high up in the foliage, and I did not want to call attention to myself by climbing the trees. I managed to get a short recording, but the singers are largely obscured by the noise of traffic. I have never seen any other records of the species any further north than Massachusetts, so this could potentially be the furthest tip of the species’ push northward. However since I was unable to collect specimens or get a good recording, this must remain an unconfirmed record.

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Dark form male Orocharis, found on the Cornell University campus in Ithaca, NY.

My most recent experiences with Orocharis have been this year in Ithaca, New York. When I first went out at night on the Cornell campus, I was blown away by the enormous chorus of Orocharis from every bush and tree on campus. Clearly this was an extremely abundant and dominant species here. I collected several individuals over the course of the fall, some by deliberate searching and others completely by accident. They were one of the last cricket species to sing in November before cold and snow silenced the orthopteran hordes; only Allard’s ground crickets and Carolina ground crickets surpassed Orocharis by a few weeks in the wild. One male that I kept inside even survived to December 27th!

Orocharis appears to be a very hardy, adaptable animal that is seemingly moving north. Although some so-called “range expansions” are simply the result of more people looking at insects today than in the past, the fact that Orocharis has a well-recognized, easily distinguished song, and also does very well in urban habitats, points to an actual northward push, perhaps due to climate change. I am fascinated by this species and will continue to document their presence wherever I go.

More information, range maps, and photos on Singing Insects of North AmericaBugGuide, and Listening in Nature.

As an aside, I find Orocharis saltator to be a very endearing pet. Their song is pleasing to the ear, and they are very easy to keep happy – just give a male a carrot slice and fish flakes, and he will sing from dusk to dawn.

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Orocharis has an adorable face!