Katydids are members of the family of "long-horned grasshoppers", so named because of their elongate antennae, and to distinguish them from the short-horned grasshoppers of the family Acrididae (for instance the granite grasshopper). Katydids are herbivores, and their mouthparts are adapted for chewing tough plant material. As far as I know they are generalist herbivores, meaning they eat essentially any plant material that is palatable, and do not concentrate on one particular plant type, which many insects do. The former type of food preference (e.g. generalists) are known as "polyphagous" (many-eating), to distinguish them from "oligophagous" (few-eating) or "monophagous" (one-eating) insects, which obviously concentrate on a few or even just one species of plant. Many insects are that specific in their food preferences. Part of the reason for this specificity is that monophagous or oligophagous insects are adapted to detoxify the secondary compounds of their preferred plant food, and enzymes that work to detoxify one kind of plant don't work on others.

The orthopterans in general are known for their auditory communication behaviors. Our field crickets use advertisement calls to attract females. Interactions between males and females, and between neighboring males, are based on auditory signals. The katydid also uses acoustic communication. Males call to attract females, although the nature of the mating system is unknown (to me at least). So we really don’t know whether males are territorial, whether males can attract multiple mates, or whether females mate more than once in their lifetimes. Katydids (of both sexes) have structures on their front legs callled tympana (singular tympanum) which are the ears of these insects. Having one on each front leg allows them to localize sounds (e.g. they can detect the direction the sounds are coming from). This is obviously an important capability, especially for males who must court approaching females that signal their approach acoustically.

Katydids are obviously cryptically colored (and structured ­ the wings look like leaves), but they are still potentially subjected to predation. Predators, especially birds, frequently catch insects by the legs (because the legs provide a good handle), and insects are frequently missing one or more legs. In fact I observed several katydids over the weekend, and many of them had five or fewer legs, presumably as a result of encounters with insectivorous birds like jays. An insect can walk around just fine on five legs (how they compensate for the loss of a leg is an involved story), and can even hobble about on four. Katydids are much better off to lose a leg to a predator than to get eaten, so they have evolved a behavior that allows them to escape if a predator grabs their leg. That behavior is "leg autotomy", which is sort of like tail autotomy in lizards, but in the case of katydids they have to actively bite off their own leg. You can experimentally demonstrate this behavior by catching a katydid with a net, placing the katydid on the ground while holding it by the wings, then grasping its leg with a pair of forceps. When you release the wings, the katydid reaches down and bites off the leg that you are holding. Sometimes this happens quickly and other times it takes a while, and how long it takes is determined by a) the gender of the individual katydid and b) which leg you grasp. Females autotomize their legs faster in general than males, and males autotomize the back legs faster than the front pair. Why this pattern of difference?