Strike Three: Mediterranean Katydids Like Vines

Sixth instar on morning glory (Ipomoea)

Today we have discovered a colony of Mediterranean Katydids (Phaneroptera nana) on a vine for the third time, piling on the evidence that they have a distinct preference for vines; this time it was grape (Vitis vinifera)!

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This is the first real year (2016) that we have really found a lot of Mediterranean Katydids (Phaneroptera nana). In the past, we have only consistently found the native and solitary Mexican Bush Katydid (Scuderria mexicana) when we look on trees, such as the apple tree (Malus domestica) in our backyard. We have never once found a Mediterranean Katydid on our apple; the one time we have found them before this year was first on a morning glory vine (Ipomoea) growing along the fence of a residential home next to Albany Middle School (Albany, CA) and also on another morning glory vine growing along the fence forming the border of the Albany Middle School campus. 

Since then, the first morning glory was removed by the owner for reasons that we do not know of and venturing out to search the second morning glory became a rare occurrence since we graduated from Albany Middle School. Instead, we attempted to find the Mediterranean Katydids in areas that we have found Mexican Bush Katydids since they are somewhat related species (both in the katydid subfamily Phaneropterinae) and would probably prefer similar habitats, but that never worked. They were never on any trees that the Mexican Bush Katydids liked (apple, citrus [Citrus], willow [Salix]) or out on little shrubs and herbs in the garden. It was only this year that we finally did go back to the middle school morning glory on 5/30 that we finally rediscovered the Mediterranean Katydid again. At the time, we just assumed that the place was a common breeding ground for the species and were not too keen as to the exact habitat and host plant preferences that led the katydids to that area. 

But now we have a pretty good idea. If you have been following our P. nana Rearing Notes, you will probably know that since finding them again at that morning glory, we have also discovered the katydids colonizing other locations, namely, the huge passionflower vine (Passiflora) and blackberry (Rubus ursinus) complex on the Ohlone Greenway at Lincoln Ave. (El Cerrito, CA). Both of these plants, like morning glory, are distinct vines. And like the particular morning glory at both the Middle School and the residential home, they were very large vines covering an entire fence (growing vertically) and in full sunshine. For a while, we were not sure whether the commonalities were coincidence or indicative of certain habitat preferences. But when we found that the katydids had also colonized a grape vine (Vitis vinifera) also growing in the same way as the other vines at a different residential home in Berkeley (about two blocks perpendicular to the Ohlone Greenway at Gilman St.) today, we are more convinced than ever that it could not be a coincidence. 

The evidence is now seriously piling on. Now, three of three different distinct locations where we have found them colonizing (Albany Middle School, Ohlone Greenway, the residential home in Berkeley), they have been on vines. And to spice things up even further, the guys at Singing Insects of North America first found the Mediterranean Katydid on a plant called Plumbago auriculata, a climbing shrub climbing on a privet plant in a similar fashion to vines. We conclude that while it probably isn't obligatory for them to breed on vines, it certainly must be preferable and we can certainly think of a few reasons why. Mediterranean Katydids, like a lot of Orthoptera, are gregarious in that the nymphs hang out in big groups (Have you ever stepped into a dry grass field and seen hundreds of grasshopper nymphs jump out or heard of locust swarms?). They need something very large to colonize with plenty of space to support so many individuals and also a place for them to hide, such as in the masses of dead plant matter underneath the vines (we have noticed that when alarmed, the katydids' first instinct is to crawl deeper into the dead vine mass). In addition, the vine is probably an excellent place for the adults to lay their eggs. In this particular species, the eggs are laid in nice big rows on slender branches such as a large vine shoot hidden deep comfortably concealed in the mass to overwinter. It is also necessary that the habitat be growing in as much open sun as possible since they love to bask in the sunlight during the day when they are resting (they are cold blooded and nocturnal), which is accomplished very well by a vine growing vertically along a fence. 

So, I guess the final takeaway is that if you are ever in California or some other place where Mediterranean Katydids have been reported (New Jersey), try to check out some big vines growing in open sun. They might just be covered in dozens of the little guys.

- Brian