Avocado leaf roller moth (Amorbia cuneanum)
This week’s crawly has a pretty cute name. Don’t worry, they aren’t going to destroy your favorite guac ingredient! Meet the avocado leaf roller moth (Amorbia cuneanum). We’ll call them “ALR” for short.
While I found the pictured ALR in Trail, odds are you won’t ever get to see one of these pretty wedge-shaped moths – or should we call them “snootiful” for that rust-colored little snoot?
Fun fact: The ALR’s Latin name “cuneanum” comes from the Latin term for “wedge-shaped.”
There are only nine recorded observations of ALRs in Oregon and a just few hundred in all of North America.
Western North American natives, they can only be found from British Columbia south to Baja, Calif., so despite their avocado moniker, no one is in danger of losing their avocado toast any time soon.
Honestly, the common name is rather unfair. As mentioned above, ALRs are native to the West Coast of the United States; avocados were imported from Mexico. So, ALRs got stuck with a panic-inducing common name for a plant that wasn’t even in the U.S. until 1833.
To be clear, their caterpillars will chow down on avocado leaves; there just aren’t that many ALRs out there.
What are they doing in Oregon if they eat avocados? ALRs, as well as many moths in their Family Tortricidae, are polyphagous.
“Snuffleupagus did you say?”
No. Polyphagous – which is almost as fun to say out loud but is very much not a Muppet.
It is a way of life. It means, “feeding on or utilizing many kinds of food.” It comes from the Greek polyphagos, “eating too much food.”
Guess we all feel polyphagous post-Thanksgiving!
So, what other plants do ALRs eat? Larvae often dine on evergreen shrubs or trees with broad, smooth leaves, manzanita, madrone, and rarely conifers. Our area is chock full of manzanitas and madrones.
Fun fact: Manzanita is a common name for many species of the genus Arctostaphylos.
There is only one madrone, however, Arbutus menziesii (our state tree.)
Now, even with the new 2023 plant zone map, our area is still just a tad too cool to easily grow avocados, but if we could we still wouldn’t need to worry about ALRs as the damage they do to their food trees is cosmetic.
Leaves serve double duty for ALR caterpillars. This brings us to part of their common name “leaf roller.” The small (one-quarter to one-half inch) caterpillars use silk to roll up a leaf of their host plant, so they have a little den to hide from predators in.
Other leaves they munch on, then return to their rolled hidey hole to rest.
Mature caterpillars may take a bite out of an avocado (or other) fruit, but again the damage is mostly cosmetic. In rare cases the fruit can be infected by microorganisms at the bite site.
With the small number of ALRs in general, and their abundance of natural predators such as tachinid flies and braconid wasps, these wedgy moths aren’t on anyone’s “most wanted” list.
The bottom line: If you luck into spotting an ALR warming up on your deck one spring morning, feel free to appreciate the pretty flitter.