The Beautiful Katydids

Piotr Naskrecki

The male stops singing and lifts his discerning than most, and he is almost body high above the surface of the as likely to reject her as she is to reject palm leaf on which he stands. His body him. In many katydids, the male’s in- shifts almost imperceptibly toward a vestment in offspring is nearly as sig- large shape in front of him. A female nificant as that of the female, and, not has finally arrived, attracted by the loud surprisingly, he wants to place it with bursts of high-frequency calls that he the best partner possible. Females who has broadcast from his perch for the are deemed too small or too weak to be last couple of nights. She is definitely good mothers will be unceremoniously interested in him, but the deal is by no spurned. means sealed. All the energy he has ex- On the leaf, the female spotted syl- pended on calling, and the dangers he van katydid (Scopiorinus impressopuncta- has exposed himself to by revealing his tus) extends her long antennae toward location to the entire world, are noth- those of the male, and for a few minutes ing but a prelude to the true test that the pair “smell” each other with their will determine whether his genes are long appendages. Suddenly, still silent, passed on to the next generation. In the male forcefully shakes his entire most the arrival of the female body, sending a series of low-frequen- signifies her willingness to mate, and cy waves through the leaf toward the her wooer is more than happy to oblige. female. She responds in the same fash- Katydid males, however, are far more ion, and for a while the pair continue

The globular white mass at the base of the female katydid’s swordlike ovipositor is the spermatophylax, the nutrient- rich gift from the male. Photograph by Piotr Naskrecki.

14 WINGS This southern African species, melanoptera, a predator, uses its large, spiny legs to catch its prey. Photograph by Piotr Naskrecki. to exchange short, silent vibrations. Sat- lax contains not only his sperm cells, isfied with her strength and size, the which ensure fertilization of the eggs, male does not retreat. As the female ap- but also a large packet of carbohydrates proaches, he lowers his body and slides and proteins, which nourish the female. under her, firmly grabbing the tip of her In some cases, the weight of this nuptial abdomen with a pair of short processes gift may exceed 20 percent of the male’s on his; he then secures her position on body weight and constitutes an enor- top of him by crossing his long hind mous contribution to the fitness of the legs over her back. For the next few potential progeny. It has been shown hours the pair remain connected, while that a large nuptial gift significantly the male produces a complex gelatinous increases the body size — and thus the structure, which he carefully attaches survival potential — of the offspring. Of to the base of the female’s ovipositor, course, not all katydid males produce her egg-laying organ. Then, after the huge nuptial meals; in some species, the pair finally separate, the female doubles only function of the spermatophylax up and begins eating it. is to keep the female busy removing it, This nuptial gift, known as the with the hope of reducing the chances spermatophylax, represents a major in- of her mating with another male. vestment on the part of the male and Katydids, known in Britain and Eu- is the reason why the male katydid is rope as “bush crickets,” are classified as often as coy as the female in selecting the superfamily Tettigonioidea of the a mating partner. The spermatophy- order . They are related to

SPRING 2010 15 principal enemies. In any case, luckily for us, courtship calls of many North American species can be enjoyed even by those whose high-frequency percep- tion is past its prime. Late-August evenings in rural New England tend to be hot and sticky, and if you close your eyes it is easy to be- lieve that you are in some remote tropi- cal location. Mosquitoes reinforce this feeling, but if you brave that minor unpleasantness you may be rewarded with one of the most beautiful aural Translucence allows this sylvan katydid landscapes on the North American (Mustius superbus) to blend with the leaf. continent. Among the multitude of Photograph by Piotr Naskrecki. bell-like tree crickets and buzzy cone- headed katydids, one sound is sure to crickets and grasshoppers, but differ stand out and make an unforgettable from them in a number of important impression on your senses — the oth- characteristics. Nearly all species of ka- erworldly, loud, and steady staccato tydids produce sound by rubbing the of the true katydid (Pterophylla camel- base of the left wing against the right lifolia). But despite the ubiquity of its one. Crickets employ a similar tech- acoustic presence, finding the singer is nique, but one that involves a different not an easy task. True katydids usually part of the wing, whereas grasshoppers sing from high perches, often twenty to usually sing by rubbing their hind legs thirty feet above the ground, and their against their wings or abdomens. Ka- green, cryptic coloration makes spot- tydid songs can be extremely loud. In ting a singing male difficult. If you are North America, the robust conehead persistent, though, and lucky, you will (Neoconocephalus robustus) produces a be rewarded with the sight of a large, call with the intensity of 116 decibels, beautiful that looks like some- a sound louder than a lawnmower or a thing that came from the steamy rain- jackhammer, although a large part of its forests of South America. And, in fact, energy is inaudible to human ears be- it probably did. cause of its high frequency. Many spe- The North American true katydid cies produce calls that greatly exceed is a member of the lineage known as our hearing capabilities, often reaching sylvan katydids (the subfamily Pseudo- frequencies above 100 kilohertz — the phyllinae), a group of that flour- upper range for the most sensitive of ishes in the tropics and includes some of human ears is about 22 kilohertz — the most spectacular examples of plant and some entomologists speculate mimicry in the kingdom. One that the main function of such high- tropical species in particular, the pea- pitched calls may be to interfere with cock katydid (Pterochroza ocellata), takes the echolocation of bats, the katydids’ its resemblance to a dried, damaged leaf

16 WINGS to the extreme. No two individuals are recent, comprehensive regional study alike in their color or even the shape anywhere in the world revealed faunas of the wing, a mechanism adapted to of katydids of which 30 to 75 percent of prevent such predators as birds and species were new to science. Even in the monkeys from learning to recognize United States, where the katydid fauna them as a potential meal. This poly- is relatively well known, new species are morphism fools not only predators, but discovered with some regularity. About also some taxonomists. A recent study 280 species have been recorded from demonstrated this unequivocally when the continental United States — Hawaii twelve previously recognized “species” has its own endemic genus, Banza, with of the genus Pterochroza were identified eleven species — but new kinds are still among the offspring of a single female! being found in the southern regions of For decades, ethologists — scientists the country. In some groups, such as the who study animal behavior patterns — coneheads (Neoconocephalus), studies of have used a handful of katydid species their acoustic behavior reveal the pres- as model organisms to study and un- ence of “cryptic species,” types that are derstand processes that govern mate virtually indistinguishable on morpho- selection and parental investment, but logical grounds but are reproductively we know shockingly little about the isolated and different in their behavior. lives of the vast majority of the more Unfortunately, as new species are than sixty-seven hundred known spe- being discovered, we are losing others. cies. In addition, there are probably two Katydids are one of the few groups of to four thousand species awaiting dis- North American invertebrates in which covery and description; virtually every the extinction of species has been un-

Many katydids have remarkably realistic camouflage. The peacock katydid (Pterochroza ocellata) resembles dead leaves; other species mimic green foliage. Photograph by Piotr Naskrecki.

SPRING 2010 17 ambiguously demonstrated, as exempli- the katydid ( thalassinum). fied by the now-extinct Antioch Dunes It is a small, pale-green species, whose katydid (Neduba extincta). As with most males are unusual for their inability to invertebrates, habitat loss is the main sing, choosing instead to attract females culprit, but North American katydids by drumming against tree bark with may face additional dangers. In many their hind legs. In some places, includ- meadows of the northeastern United ing my own garden near Boston, this States you are less likely to encounter outsider is now the only species found. any of the native shield-backs (Atlan- Although the general perception of ticus) than you are an invasive Roesel’s katydids is that of green, leaflike, and katydid (Metrioptera roeselii). This ag- rather dull herbivores, across the globe gressive, predaceous species came from they have evolved into a multitude of Central Europe, probably sometime at shapes, sizes, and lifestyles. In south- the beginning of the last century, and ern Africa, giant predatory katydids has been spreading like wildfire along (Clonia) spread their muscular, spiny the East Coast and steadily moving west. legs to catch cicadas and beetles, while Although nobody has yet looked at the in the forests of Costa Rica rhinoceros actual impact of this species on local katydids (Copiphora rhinoceros) prey on katydids, the fact that it hatches and snails and lizards. In Australia, pollen- matures earlier in the season than local feeding katydids (Zaprochilus) extract species do — and then feeds on young nectar and pollen from the flowers nymphs of other species — is bound to of trees and bushes; and in Tibet the have serious implications for the native black Hyphinomos ekes a living among fauna. Woodlands of the Northeast are patches of ice sixteen thousand feet also full of another European arrival, (forty-nine hundred meters) up in the

The oak katydid (Meconema thalassinum) is a European species now well established in North America. Photograph by Piotr Naskrecki.

18 WINGS This katydid (Hetrodes pupus) is well protected by the armored plates on its body, but if those fail it sprays the attacker with its own bitter blood. Photograph by Piotr Naskrecki.

Himalayas. The diversity of shapes just begun to discover potent chemical among species of katydids, such as the defenses present in some species. Katy- sticklike Phasmodes and the armored, dids are beautiful and fascinating ani- tanklike Hetrodes, is so great that it is mals that in many ways help us under- hard to believe that these insects are stand the world around us. It would be members of the same lineage. But this nice to repay the favor by making sure is what makes them such interesting that we allow them to continue their subjects of research. We know, based very existence. on both morphological and genetic data, that they are all closely related to each other, and we can now trace Piotr Naskrecki is a research associate at the historical and evolutionary forces the Museum of Comparative Zoology at that shaped their bodies and behaviors. Harvard University, where he works on the Ecologists use katydids to assess evolution and systematics of orthopteroid the level of habitat disturbance, often insects. He is also involved in a number applying methods that rely solely on of invertebrate-conservation projects, in- the unique acoustic signatures of each cluding the IUCN Red List assessment of species, and physiologists tap into their African katydids and the development of nervous systems to understand the na- internet-based identification tools and ture of hearing. Ethologists continue to resources for invertebrate biologists and disentangle the intricate rules of their conservation practitioners. As a writer courtship in order to explain what lies and photographer he strives to promote behind the often mysterious choices of the beauty, value, and conservation of in- mating partners, and biochemists have vertebrate animals.

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