Roesel’s Katydid, Long-Winged Form

2015 April 1

Sam found this in town on July 27, 2014, when we went to Culver’s for ice cream. She said the long jumping legs were missing when she found it (which was probably why she was even able to catch it).

This is actually a species we’ve seen before, Roesel’s Katydid. The difference is that last time we had the short-winged, flightless form, while this is the long-winged, migratory form. Aside from the long wings, it has the same pattern of yellow marks on its thorax as we saw last time.

These are an invasive European species that has been spreading across North America since they were first noted in Montreal in 1953. The long-winged portion of their population, like this one, evidently are key in spreading them around rapidly. Apparently, the long-winged ones aren’t genetically distinct from the short-winged ones. What happens is more like this: If the katydids are well-fed and growing rapidly, they devote more of their resources to body growth and egg production, and not so much to the wings. Under these conditions, only about 1% of the population has large enough wings to use for flying. But, once their population builds up to where they are crowded, they grow more slowly, giving time to develop longer wings. The much higher proportion of long-winged specimens, like this one, can then fly off to relieve the population pressure.

Luckily, they don’t appear to be really serious agricultural pests, and are just fitting into the regular grasshopper/katydid niche without much disruption. Although, they are reported to be omnivorous (and inclined to bite, so that back in their homeland in Europe they are sometimes known as “wart-biters”), so they may prey on other native species given the chance.

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