A Tiny Russian Doll Mystery

I started noticing them weeks ago. Small oval leaf chips on the ground. The bright leaf-green color stood out against the orangey-brown forest floor.

At first, they were few and far between. I assumed they were uneaten bits falling from a caterpillar banquet far above. As the days passed they became more and more numerous, and I realized they were curiously similar in size and shape.

Not what one would expect from random leaf-munched leavings.

I also started finding leaves on the ground, filled with holes the size of the mystery chips. The leaves were usually from maple trees.

I eventually picked up a leaf chip for a closer look. It was actually two leaf chips, stuck together with silk. I found nothing inside but a bit of frass (the technical term for insect droppings. This word should be more widely known. It's a good word).

Whoever was living inside the little leaf sandwich, it had vacated the premises. Perhaps it had wriggled free while I was breaking and entering, and I hadn't noticed. The leaf chips were tiny after all - only about a half inch across - so the tenant must be even tinier.

Silk meant either spiders or caterpillars. But spiders don't have the right sort of chompers for cutting leaf disks. That left caterpillars. Lots of moth species create homes for themselves inside silken-shrouded leaves, although I didn't know of any that made tiny clamshell apartments. And why were they dropping to the ground? It seemed a poor strategy to literally cut yourself off from your food source. Perhaps they were getting ready to pupate in their little leafy cocoons.

I pried open another leaf chip, and this one had a second, smaller pair of leaf circles inside. But inside of that? Still empty.

Over the next several days I peered inside a few more of the leafy mini-mysteries, and I finally found someone at home. Under the first layer of leaves was another layer of leaves. At the center of this minuscule Russian doll was a tiny, translucent caterpillar.

Not too long ago, this would have been about as far as I could take the mystery - unless I put some leaf chips in a jar and hoped that pupation and hatching would occur. Until recently, identifying caterpillars and other insect larvae wasn't easy. Field guides generally focus on charismatic and relatively simple-to-identify adults. Even today, the larval forms of some moths are unknown.

But things are changing. The internet is revolutionizing the ability to identify (and learn more about) all manner of living things. For example, I'm a regular user of iNaturalist. This is 'a nonprofit social network of naturalists, citizen scientists, and biologists built on the concept of mapping and sharing observations of biodiversity across the globe'.

Following a few simple rules, you can upload photographs of living things, and make the images available for anyone and everyone to weigh in on what they might be. You can also use your own expertise to help identify organisms from around the world.

There are currently about 300,000 active users of the site, and about 200,000,000 observations have been made.

The site also features an AI that will provide its own identification opinions. It's better at some taxa than others, but best of all, it's immediate.

I didn't have much hope for an immediate identification of my tiny, nondescript blob of a caterpillar, but to my surprise, the AI informed me that it was likely a Maple Leafcutter Moth (Paraclemensia acerifoliella). iNaturalist didn't offer much background information on the species, but a quick Google search provided a delightful write-up, which you can enjoy at the link below.

The internet may be rife with scams, misinformation, and preternaturally crabby people, but it also provides exceptional resources for curious naturalists. Resources that would have been hard to come by, just a few decades ago. Hooray for an appropriate use of technology!