A Mystery Confounded Leaf Bug Experts for Over 100 Years Until Ph.D. Student Royce Cumming Solved It

Royce Cumming (Credit: Sierra Teemsma)

“The walking stick and walking leaf community is very small,” says Royce Cumming. “Everyone knows everyone.” This turned out to be a fortunate thing for Cumming, a second-year Ph.D. student in Biology who solved a mystery that’s more than a century old. 

A few years ago, he started publishing his findings on leaf insects, and people around the world started sending him pictures of their specimens. One was Stéphane Le Tirant, a world-renowned expert at the Montreal Insectarium. Le Tirant, who is “primarily a beetle guy,” according to Cumming, also collected leaf insects, and asked if he could send Cumming all of his pictures.

The next morning Cumming woke up to 15 emails from Le Tirant of the species in his collection. Cumming, who had become known as an expert himself in this niche within the insect world, was able to put names on all but one of the species Le Tirant had on hand. Over the next two years, every few months, Le Tirant and Cumming would get a new email from another curator who’d gone into their collection and opened up their drawers. “And sure enough, there were more undescribed species,” Cumming says. 

In the midst of this flurry of discovery, something remarkable happened. 

See the photo gallery full-screen.

In the spring of 2018, Le Tirant received 13 eggs laid by a captured leaf insect in the Phyllium asekiense species, found in Papua New Guinea and known only from female specimens. The eggs yielded five nymphs, of which only three lived to adulthood. One nymph grew to mimic a wide, green leaf, like its mother. But the other two resembled sticks and grew wings, looking like leaf insects in the Nanophyllium genus, which was known only from male specimens. 

Le Tirant sent a picture to Cumming, who verified a hunch the two scientists already had: There weren’t two species, but one. In a recent paper, Le Tirant and Cumming announced their finding, finally uniting males and females in one species: Nanophyllium asekiense

The puzzle that Cumming and LeTirant solved had mystified entomologists since 1906, when the Nanophyllium were first observed. Leaf insects, Cumming explains, are hard to find, as they are experts at camouflage. (He has yet to observe one in the wild.) Males and females also differ drastically in appearance. “Because they’re so sexually dimorphic,” Cumming says, “if we don’t have DNA sequences to match them up or people raising them, sometimes we don't know which males go with which females.” 

As compelling as they may seem, stick and leaf insects aren’t the stars of the insect world. “Because they're not really an agricultural pest and they’re not as much in the public eye like butterflies, they don’t receive gobs and gobs of government funding,” Cumming says. Most stick and leaf insect people study the bugs as a “work of passion.” “Whenever someone finds a new species, everyone gets excited because they’re always absolutely gorgeous and really, interesting looking,” Cumming adds.

Cumming grew up on a ranch in California. “I was always outside and collecting a little bit of everything.” But he wound up studying business administration as an undergraduate. “I had always loved entomology and I wanted to keep it just to be my hobby on the side to enjoy.” Yet he began working with a forensic entomologist ⎯ a very small field (even compared to what he does now), involving perhaps a few dozen practitioners who work primarily on homicides: analyzing insect evidence, such as flies found at a crime scene, that can help determine how long ago a victim died. [For more on that, see box below.]

Eventually, he realized that he was getting paid to do what he loved. He completed a master’s in forensic entomology, and by 2016, began studying leaf insects nearly by accident. A friend sent him some specimens, and when Cumming consulted the existing literature, he discovered that “they didn’t match up with anything that was known.” He dove in to solve the mystery, translating old German texts and reaching out to stick and leaf insect experts, most of whom are in Europe. As he started to develop a taxonomy, the emails came flooding in from people like Le Tirant. 

In 2017, Cumming was sent a number of specimens from the Philippines. He contacted Professor David Lohman at City College and The Graduate Center, who works on butterflies in Southeast Asia to sequence the samples and allow them to match up the female and male specimens. During spring break from his master’s program in Indiana, Cumming drove to New York and met with Lohman, who mentioned the prospect of doing a Ph.D. at CUNY. 

Cumming was in New York for just 8 months when the pandemic struck. He went back to his home ranch in the Salinas Valley, in the center of California, near the coast. 

“It’s kind of weird here on the ranch, because you would never know there’s a global pandemic happening,” he says. Yet it has been an incredibly productive time for him. “It was actually fabulous to be able to spend so much time here. I’ve been getting more into botany. And so, I was able to go out and I’ve been recording every species of plant that I can get my hands on.” 

What’s it like to find a new species? It’s still fabulous, even when almost every month you come across a new one. “It seems every island and every mountaintop has a new leaf insect species,” Cuming says. “Right now, I’m working on describing 59 species, and we are finding new species faster than we can publish them”. 

Cumming’s dream find is “a live specimen of one of those rare species that were described from one specimen and have not been seen in 200 years. To be able to find one of those alive would be kind of the Holy Grail,” he says.

Cumming still hopes to see a leaf insect in the wild. “I was supposed to be spending a month in Southern Philippines doing field work and then I was supposed to be in New Guinea, which is a biodiversity hotspot for leaf insects, for a month. So, this was my year to go out and finally get to see some lovely live specimens in the wild but COVID had other plans.”

Next up for Cumming is revising the phylogeny, or evolutionary history, of leaf insects. He is looking at the DNA of different species to determine how they are related to each other and to understand how past geological events going back millions of years influenced their evolution. It’s an enormous effort but, like everything leaf insect-related, one of love. He explains the intrigue. If we found life beyond Earth, we’d immediately want to classify it and determine how it evolved. “We’ve been trying for hundreds of years to answer these big questions” for life of Earth, Cumming says. “For the insects, we're just a drop in the bucket as far as knowing what we actually have in our own backyards.” 

 

Maggots, Flies, and ‘Stinky, Bad Bodies’: Forensic Entomology Is His Sideline

As a forensic entomologist, Royce Cumming helps law enforcement officials solve cases involving murder and death. He can determine — to within a few days — when a person died, based on the ages and types of flies and maggots that are feeding on the corpse. An insect’s stages of growth are predictable, Cumming explains. “If you know the temperatures in the area and the species in the area, you can get a pretty good window of time as to how long a body’s been decomposing.” Unlike forensic pathologists and anthropologists, who analyze either recently deceased individuals or ones long dead, forensic entomologists assess “the highly decomposed, juicy, stinky, bad bodies” — corpses that are between a few weeks and few months old — “because those are the ones that are in active decay with tons and tons of insects feeding on them,” Cumming says. He estimates he’s one of about 40 forensic entomologists in the country and, of those, about half exclusively teach. It’s “a little bit of work but every now and then, but we can be very significant to a case and can help bring justice.”

Submitted on: DEC 18, 2020

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