During the early days of the coronavirus
pandemic, some of us mastered bread-baking (if we could get our hands on flour)
or devoted ourselves to nurturing some new mail-order houseplant.
اضافة اعلان
Charley Eiseman set the bar a bit higher, as he
always does. In 2020, he decided to keep count of certain creatures living
within the confines of his Northfield,
Massachusetts, yard — and not the easy
ones, like birds or mammals, either.
For Eiseman, a freelance naturalist who conducts
biodiversity surveys for conservation groups and other clients, it is the
little things that matter most.
Before the year was out, he had recorded 212 leaf
miner species, among his various tallies.
You may not be familiar with leaf miners, but even
if you haven’t seen the miners themselves, which typically go unnoticed, you
have most likely witnessed their handiwork: the squiggles or blotches within
leaf tissue, known as mines.
The tiny creatures that excavate a leaf’s epidermal
layers to feed themselves are larvae from some 50 families of moths, flies,
beetles, and sawflies. Each species targets particular host plants in ancient,
intimate relationships.
If you grow columbine (Aquilegia), a popular meal in
many regions for larvae of flies in the genus Phytomyza, you have probably seen
evidence of the presence of a leaf miner — marks that you feared were symptoms
of disease, but aren’t.
Eiseman is also a keen observer of the architects
behind galls, those abnormal growths that can take the shape of
Ping-Pong balls
when they form at leaf buds, or blisters or conical knobs when they project
from the foliage surface.
We gardeners may view these growths as
disfigurements, asking our local nursery staff (or Google) how to “fix it”. But
nothing is broken. It’s usually just some insect — often an aphid, midge, or
wasp — setting up housekeeping or building a nursery to raise their young.
Eiseman identifies these leaf mines and galls with
forensic precision in the name of his own insatiable curiosity — and for
another reason: “I would love to put out a major message: If you see evidence
of things eating and living on your plants, that is a good thing.”
He is not talking about invasive species like spongy
moth caterpillars or Japanese beetles; those he does not celebrate. Otherwise,
though, he believes we should try to let go of the reflexive alarm of
“something’s harming my plant”.
At issue is biodiversity, which is damaged by our
relentless pursuit of garden perfection and unblemished leaves. The more
insects and other invertebrates that Eiseman sees engaging with plants, the
happier he is.
“I know other people don’t feel the same way about
bugs,” he said. “But if you like any living things — like birds or frogs or
whatever else — they pretty much all eat insects, or eat something else that
eats insects. If you don’t have that base of insects, you’re not going to have
those other things.”
The unflashy supporting cast
As Eiseman examines a spider
web for clues to which species made it, or peers at a folded leaf to assess
which insect may be sheltering inside, he is ever on the lookout for what is
described in the title of a field guide he wrote with Noah Charney in 2010:
“Tracks & Sign of Insects and Other Invertebrates: A Guide to North American
Species”.
That book emphatically reminds the reader that
nature is not all brightly colored flowers and male birds’ breeding plumage.
The mostly unflashy invertebrates are the ones who often perform the most
crucial roles — they are “the little things that run the world”, in the words
of the biologist E.O. Wilson.
Eiseman’s motivation for writing the book was purely
pragmatic. While doing fieldwork, he would find himself taking pictures of odd
things and would jot a note to himself to look them up later and identify them.
“And then I realized that there was no book to tell
me what these things were,” he said. “So I ended up writing the book, so I
could learn all of that stuff.”
To further satisfy his need to know, Eiseman wrote
an e-book on leaf miners and founded a North American leaf miner project on
iNaturalist, the online community where nature lovers seek plant and animal
identifications and contribute sightings. More than 1,500 people have
contributed over 50,000 leaf miner observations there, representing over 800
species.
Inspiration in a poison ivy leaf
Leaf miners and gall insects
are both parasitic, living inside plant tissue. While miners spend their time
excavating, Eiseman said, gall insects are “actually manipulating the growth of
the plant to create this shelter that they then live and feed inside”.
Gall insects are everywhere: It is estimated that
1,000 species of gall wasps in North America are responsible for the galls on
oaks alone.
Eiseman was
familiar with galls long before writing his first book, particularly the common
ones referred to as “oak apples”, for their large size and roughly spherical
shape. You may have seen them on the ground, either freshly fallen and green
(sometimes with dark polka dots) or after they have dried and faded to resemble
brown Ping-Pong balls.
The leaf mines — those serpentine tunnels within
layers of tissue — revealed themselves to him later, alongside a Vermont trail,
courtesy of poison ivy with blotchy patches on its foliage.
Sitting on a leaf were two tiny moths, with the
pupal skins they had just emerged from still poking out of the leaf mines. He
filed that information away and later came upon a reference in an old book
describing a moth, Cameraria guttifinitella, that makes such blotches on poison
ivy.
“It suddenly kind of clicked with me that if you
know what the plant is and what the pattern is, you can identify these things
to species just by looking at that pattern,” he said. “I got fascinated with
that idea, and I’ve spent the past decade trying to learn all of those
different patterns on leaves and stems.”
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