Orthoptera Thursday: The Katydid's Menu

Carnivorous katydids? That might come as a shock, but in reality, many members of the order Orthoptera, which includes katydids, grasshoppers, and crickets, are omnivorous to at least some degree. This broad diet is one reason these insects are so successful. Let’s take a closer look at one subset of katydids in particular.

A female Orchelimum sp. meadow katydid.

Katydids are also known as longhorned grasshoppers, for their exceptionally long, thread-like antennae, in contrast to true grasshoppers that have shorter, thicker antennae. Katydids are in the family Tettigoniidae. Most katydids are green, brown, or gray in color, though tropical species can be stunningly colorful.

Meadow katydids and conehead katydids form the subfamily Conocephalinae. They are among the most abundant of orthopterans in the eastern United States and adjacent Canada. At this time of year they have reached maturity and are seeking mates. Taking a stroll through tall grass, especially in wetlands, lush meadows, or prairies will flush countless individuals.

A female conehead katdid, Neoconocephalus sp.

A substantial portion of the diet for these katydids is grass seeds, and they have mandibles (jaws) powerful enough to crack them. Conehead katydids are the largest, some members of the gens Neoconocephalus exceeding seven centimeters (nearly three inches). I can tell you from personal experience that you do not want to get bitten by one of them.

A male conehead katydid peers from dense grass.

Meadow katydids and coneheads also feed on forbs, defined as any flowering herbaceous plant that is not a grass, sedge, or rush. The insects feed on the leaves and flowers of those plants.

The impact of katydids on plant communities is not negligible. One study revealed that a population of three meadow katydid species turned nearly 16% of the biomass of a rush species (Juncus) into katydid biomass (Parsons and de la Cruz, 1980).. Damage to seeds developing in flowers resulted in a 30-50% decrease in in seed production of rushes and grasses, too.

A female lesser meadow katydid, Conocephalus sp., feeds herself a grass seed.

Watching a katydid eat is a delightful experience. They are surprisingly nimble, and will use their front tarsi (the “feet” on their front legs) like hands to direct the morsel into their mouths. It is very much like any mammal feeding itself, using its paws.

A male Orchelimum eating an acanoloniid planthopper.

Plant matter has relatively little protein and fat, so those compounds need to come from elsewhere for a katydid to prosper. Consequently, some species, especially the meadow katydids, have evolved to become opportunistic predators on other insects, especially if those insects are injured.

The insects usually encountered by katydids are other species that are herbivorous in the same habitats occupied by the katydids. This includes leafhoppers, planthoppers, and even smaller katydids.

A female Orchelimum feeding on a female smaller meadow katydid, Conocephalus sp. The victim had just mated.

Female katydids need extra protein to nourish the development of eggs, and they get a surprising assist from males. During copulation, the male delivers a sperm packet called a spermatophore. The spermatophore consists of the sperm container (ampulla) and a gelatinous mass called a spermatophylax. This is an expensive gift for the male to produce, but it is less likely that a female will mate again once she is provided this nutritious investment. This is especially true for larger meadow katydids, genus Orchelimum.

The spermatophylax consists of protein, water, some carbohydrates, but few lipids (fatty acids). The female consumes this after mating occurs, along with the rest of the spermatorphore, which protrudes from her genital tract after its insertion by the male.

A pair of meadow katydids, Orchelimum sp., just beginning to mate.

The spermatophore is perhaps one step away from sacrificing yourself entirely to your mate. Science weighs the concrete costs and benefits of such transactions, but perhaps something more meaningful is lost in the translation. The more we learn about the insect nervous system, the shorter the distance between “them” and “us.”

The jelly-like spermatophore forming where the pair are joined.

Sources:Gwynne, Darryl T. 2001. Katydids and Bush-Crickets: Reproductive Behavior and Evolution of the Tettigoniidae. Ithaca: Cornell University Press (Comstock Publishing Associates). 317 pp.
Parsons, K.A., and A.A. de la Cruz. 1980. “Energy flow and grazing behavior of conocephaline grasshoppers in a Juncus roemerianus marsh,” Ecology 61: 1045-1050.
Thornhill, Randy and John Alcock. 1983. The Evolution of Insect Mating Systems. Cambridge: Harvard University Press. 547 pp.

I Am Not a Scientist

It’s cute when someone mistakes me for a scientist, presumably because I have written books about insects, made public presentations, and am active on social media. There are occasions, though, where the confusion wastes the other party’s time, and for that I am truly apologetic. I am still a reliable source of factual information, but please allow me to set the record straight.

This post is prompted by an email exchange I had recently with a dear friend and colleague who truly is a scientist, seeking my help with a project.

Them: “I have a favor to ask….

For the past [few] years I have been conducting a long-term….survey at different nature preserves….in the hopes of trying to get a better idea of conservatisms of these insects….Ultimately I want to be able to look at a species list of insects found within a natural community or natural area and determine….which sites provide high quality critical habitat for plant community specialist insects, separate from the plant C values ranks.

The problem is few people are familiar with a wide diversity of insects. Most experts just know a particular family of insects….I have ranked all 371 taxa based on my field expertise. I'm teaming up with a dragonfly specialist for the statistical analysis. [They have] some experience with developing conservatism ranks for dragonflies and is trying to apply this to my data.

Would you be willing to take a look at the list and provide numerical ranking for the species you readily recognize? I know [specific region] isn't your main stomping ground, but you do know many of the more common species, and your ranks would be most helpful.

If you are interested in getting involved and reviewing our work for a future publication, and possibly coauthoring with us, we are open to that….My goal is to bring attention to the insects here in [specified state].

Let me know if you have any questions.

Thanks so much.”

Me: “I am flattered by the request, and would be willing to help....if I understood the assignment. I have no idea what a "C value" is. I could potentially rank them in terms of the frequency with which I see that particular genus or species on a particular plant. That can still vary significantly from one year to the next. This year, in our area, insect numbers are down significantly. I am not seeing many insects….

If there is a concrete definition of C values, then please provide it. I may or may not be able to assist. Math is my greatest weakness, and I never took statistics (not that it would even be useful given that I was in college in the early 1980s).

I am a writer and sci-comm professional, all else comes in no particular order after that.”

Them: “Yeah, don't ask me to explain statistics either. That's why I team up with the survey biologists.

As far as I know the concept of the C value (or coefficient of conservatism) came about in 1979 to reduce subjectivity in the evaluation of plant communities by placing the subjectivity up front. All plant (or other taxa) are assigned a numeric value that [provides] assessment natural quality repeatability.

In basic terms, ‘how likely is this taxa found in a high quality community?’….It's not just how common it is, though that is a factor as high quality (conservative) species are typically found only in rare habitats and thus are less likely to be encountered. The numbering is from 0-10. Almost all state-listed species are assigned a value of 10….A goldenrod soldier beetle (Chauliognathus pensylvanicus) might be a 1 or 2 as they are common [pretty much everywhere].

We also ask that you rate your confidence level 1 - 3 (3 being very confident in your rank and 1 being much less familiar with the species).

Does that help?”

Me: “Yes, that does help. I am not qualified to undertake that, being unfamiliar with [those] ecosystems at *that level*….I'm sorry, but I would potentially be doing more harm than good if I took a stab at this.

Sorry!”

Them: “….

The point is to ask. I realize it's specialized. If others are unable, then that's part of our argument - we get the best data we can. I don't know if any of this is possible but I'm going to keep at it. The more I do the more I learn.

Thanks”

Me: “My comment wasn't an indictment, apologies if it sounded that way.

You are vastly more capable than I am, and have much more experience in that kind of habitat. Maybe someone at [non-profit organization] can help?

Maybe I do not make it clear enough to anyone that I am not as much an entomologist as an ‘insect identifier.’"

Them: “I didn't take it that way. No worries.”

There is another aspect of my personality at play here. I am inherently lazy. Community science is hard work, with demanding and specific requirements for projects aimed at collecting data. That is not what interests me. I am all about recruiting potential community scientists by sharing fascinating facts and personal experiences. Heck, if I can get someone to put down the fly swatter in favor of a magnifying glass, mission accomplished.

I want to change the behavior of the average Joe or Jane who despises insects and wants them gone. Humanity as a whole, and the entire planet, for that matter, cannot survive the continued loss of biodiversity and insect abundance. More to the point, I can’t survive it. Exploring the natural world and finding insects is one of the few exercises keeping me reasonably sane, and giving me a sense of purpose. Without the “bugs,” I vanish, too.

Spider Sunday: Red Velvet Jumper

Whenever I discover a species new to me, I am compelled to illuminate the known biology of the organism for anyone who will listen, or read. This happened recently, when I encountered a little jumping spider on a sidewalk during a late afternoon walk here in Leavenworth, Kansas, USA, on August 20.

I managed to capture the creature in a plastic vial, to take home for closer observation. At the time, I anticipated that it would be an immature male in the genus Phidippus, as they are common, especially along this pathway through lawn and wannabe prairie that parallels a major street on the north end of town.

I am prone to neglecting or procrastinating in taking photos of captive specimens, so it was August 25th before I finally sat down for a spider photo shoot in the white casserole dish we have dedicated as a “studio” for insects and arachnids. I was fortunate the spider was still alive, albeit perhaps a little more slender than when I first found it.

Throughout the process of capture and photography, the spider was surprisingly slow, which is not at all like most of the fast, bouncy jumpers that I am familiar with. Viewing my photos, it became apparent that whatever this spider was, it was a mature male (fully formed terminal segment on each pedipalp); and it lacked the iridescent chelicerae (jaws) of most Phidippus species.

Puzzled, I uploaded some of the photos to my Facebook page in hopes that some of my friends who are spider experts might be able to point me in the proper direction. It was after posting that I tried looking in some of my books to see if there was anything remotely similar to my specimen. The family Salticidae is highly diverse, and not every book about spiders will include every genus, let alone species. This time I got lucky.

I soon received replies to my social media post, the first of which was from Sarah Rose, author of Spiders of North America from Princeton University Press. That field guide does not include the species she suggested: Ghelna canadensis, but I reached the same conclusion in perusing Common Spiders of North America by Richard A. Bradley. Ian Wright also suggested the genus in his comment on the Facebook post, and Alicia Lips and Dani Marie agreed. Alicia included images of a female of the species that she found on her front porch in June of this year.

Ok, more about the actual spider. The community science platform iNaturalist gives a common name of Three-lined Ground Jumping Spider for Ghelna canadensis. Somewhere I recall reading the name “Red Velvet Jumper,” but that could apply to many other species, even though it is appropriate to the color and texture of this one. Most sources offer no common name. Mature males measure 4-5 millimeters in body length, females 4.6-6.4 mm. Females are darker, gray or brownish, with indistinct markings.

This is a ground-dwelling species, unusual compared to the arboreal species in its cohort, the subtribe Dendryphantina. It occurs over much of the eastern United States, except for the southernmost tier. Data points on iNaturalist have it as far west as Minnesota in the north, and near Dallas, Texas in the south. The "Checklist of Kansas Jumping Spiders" mentions records in Douglas and Jefferson counties, but not Leavenworth. Older references may use the former name, Metaphidippus canadensis. There are also three other species in the genus Ghelna, at least one of which, G. barrowsi, also occurs in my area.

After I finished the photo session, I provided the spider with some water from the tip of a soaked cotton swab. He was thirsty! Then I took him back to where I found him, releasing him well off the sidewalk this time.

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Guarisco, Hank, Bruce Ctuler, and Kenneth E. Kinman. 2001. “Checklist of Kansas Jumping Spiders,” The Kansas School Naturalist 47(1): 1-13.
World Spider Catalog
GBIF
Bugguide