Tuesday, September 27, 2005
Scudderia Trek: Generations
This is a very young katydid nymph balancing on a pennisetum setaceum flower. I would say the species is the forktailed bush katydid, scudderia furcata. Someone named Scudder described the species in this genus, and so all these very adorable stiped-legged and banded antennaed katydids are named after him.
Katydids are closely related to grasshoppers; both have very cute young, and though I have never known them to be much of a problem in the garden or landscape, katydids like grasshoppers can be agricultural pests. An important component of a control program for pest species is a clear understanding of the life cycle and population dynamics through the year. The UC Davis IPM site states these katydids produce one generation per year, with the nymphs appearing in April/May and maturing in 2 to 3 months. How do my observations connect with this information?
The following photo sequence follows a hypothetical Forktailed Bush Katydid's life in the following steps:
1. An adult photographed on August 4.
2. Here is a fairly young, extremely cute nymph on August 14. Is this individual on of the first one's offspring? If so, in my locale the nymphs emerge quite a bit later (3.5 months later). Or is this a member of the second generation? It's possible if her parent hatched in April or even May. Hmmm.
3. Here is a more mature nymph observed on September 16.
4. And here is an adult dying possibly of old age or disease on Sept 18, just about two months after the fairly young and terribly cute nymph pictured on 8/14. (btw, The small spider here was actually tending the katydid, which was still living, as prey)
The photo at the top of this post of the very young katydid, probably just a few days after hatching, was taken September 23; I'm thinking this must represent another generation. Either we have at least two, but maybe three generations of FBKs, or there's some mechanism that staggers development stages of the "one" generation over at least 6 months--ie what is the life span of an adult individual?; or the UC Davis info is based on a much colder climate.
One thing is known for sure, these little katydids are very very very cute, and so it would be good to know when they emerge just so you could have a look.