Anita’s Blog – Lichen It Or Not
- jjvanm
- Jul 29
- 5 min read
Not just another moth story . . .
Tamaulipan lichen moths frequent my moth sheet. Less frequent are thin-banded and one-banded lichen moths – all three look the same at a brief glance with their wings folded.
Below, from left: Tamaulipan lichen moth, thin-banded lichen moth and a one-banded lichen moth, showing pinkish hind wings. (Photos by Anita Westervelt)
I’ve had other lichen moths visit the moth sheet: Dyar’s Lichen moth and pale lichen moth both of which look plain at first glance, but they’re not. There’s nothing plain about the painted lichen moth which is colorfully striking with bright orange-red and gray-black forewings, pinkish hindwings and a wingspan of 1 to 1 ½ inches.
Below, from left: Dyar's lichen moth, pale lichen moth and painted lichen moth. (Photos by Anita Westervelt)
Interestingly, in the insect kingdom, that color combo, yellow/orange/red with black, is referred to as flame-family colors or aposematic coloration.
“It’s a visual warning to potential predators that the insect is toxic or distasteful because it contains chemicals that it ingested and metabolized as a larva and retained through metamorphosis into an adult. A well-known example is the monarch butterfly, which gets alkaloids from milkweed.” Source: An online blog post, “A Way to Garden,” by Margaret Roach, interviewing Seabrooke Leckie, co-author of the “Peterson Guide to Moths of Northeastern North America.”
Some species of lichen moths, including painted lichen moths, are expert poop-flingers as caterpillars – who would have thought, right?!
“They have a specialized “comb” that folds under their body at their rear end; when they need to fling a pellet, they force haemolymph (insect blood) into the last body segment which causes the spring-loaded comb to pop out and eject the pellet – it can be tossed as far as 30 (caterpillar) body lengths away. This behavior is believed to be intended to foil parasitic and predatory wasps and flies that hone in on prey using the volatiles (evaporating chemicals) in the pellets.” (Same source as previous paragraph.)
Tamaulipan lichen moth, according to BugGuide.net, is found in subtropical thorn woodland in south Texas; the larvae eat Psychia (leafy) lichen, growing on the bark of Texas Ebony; adults feed on nectar.
Thin-banded and one-banded lichen moth caterpillars eat lichens and algae; adults feed on flower nectar and plant juices.
Pale lichen moth – caterpillars feed on lichens, preferring the algae component that grow on tree bark; BugGuide.net. Adult feeding is undocumented.
Dyar's lichen moth caterpillars eat lichens and tree algae growing on the bark of trees. Adult moths do not eat solid food; rely on energy they stored up while growing as caterpillars
Painted lichen moth – caterpillars eat lichens, algae and moss found on tree trunks. Adults do not eat, they lack functional mouthparts; they rely completely on energy stored up from when they were caterpillars to mate and reproduce during the summer months.
The Lichen.
I have a good number of lichen photographs uploaded to iNaturalist.org; Two observations of Golden-eye lichen, Teloschistes chrysophthalmus, are the only two at research grade. One photo was taken in Hugh Ramsey Nature Park in Harlingen, the one below in Falcon State Park at the western edge of Starr County.
Lichen is an odd thing. Identifying lichen to species from a photograph is frequently very difficult or impossible. Many species require microscopic examination of spores, chemical spot tests, or even DNA sequencing to tell them apart, according to an iNaturalist Community Forum.
Mostly the lichen I find is not too colorful, usually decorating tree branches quietly in pale shades of light green and gray/green. It’s not always noticeable until a dead branch falls from a tree, heavy with the slightly monochromatic but artful lichen. Staring into the depths of a batch of lichen is quite intriguing, the forms are beautiful, like a coral garden on a tree branch.
What it’s not.
Lichen grows and looks plant-like, but it’s not a plant. They have no stems, roots or leaves. Lichens are not parasites and do not feed on trees; they simply use the bark as a surface to sit on.
What it is.
Lichen is the result of a symbiotic relationship between a fungus and an alga or a cyanobacterium (bacteria commonly known as blue-green algae) – and a third element – a support, like a tree branch. It’s a harmless partnership that uses tree bark only as a surface to sit on; lichen get food from the air and sunlight rather than taking nutrients from a tree. Lichens provide food and shelter for many small animals and nesting material for birds like hummingbirds and vireos; frogs eat lichen, according to Texas A&M Forest Service.
Generally, lichens are classified into three basic groups: crustose (crusty or flaky), foliose (papery or leafy), and fruticose (stalked or branching).
A dozen years ago, I attended a lichen lecture. As long as I’ve known about lichen and lichen-laden branches falling from the sky, it’s been a mystery as to which came first, the lichen to the tree branch causing death, or an already ailing tree branch attracting lichen spores. Unintentionally, I’d stumped the lecturer. But I’ve finally found an answer.
Lichens do not target stressed or dying branches, but they do grow more abundantly on a stressed branch. Why that is, is that stressed or dying branches lose their leaves and thin out, letting more sun through, according to Biodiversityworks.org. Lichens need that extra light to grow fast. Furthermore, declining trees and branches grow very slowly, meaning the bark stays in place longer without shedding, giving lichens time to spread.
Lichens do not actively pick or choose a tree branch. Instead, wind, rain, or animals carry tiny reproductive fragments or spores to random, stable, porous surfaces, including rocks, fences, and statues, not just tree branches.
Lichens are unique, growing in artsy, swirly, feathery, textured and leafy looking shapes, and little round apparatuses that could pass for inflorescences but are more akin to the suction-cup-like toe pads of a tree frog.
There are more than 20,000 different kinds of lichen, in a variety of colors and shapes, found on every continent, from humid forests to frozen areas and desert sands. Lichens are among the hardiest and most resistant of all plant organisms. They can stand long periods of drought, incredible heat, and freezing temperatures, making it possible for them to live where nothing else can, according to tpwd.texas.gov/publications.
It is undetermined as to what species of lichen may be found in Texas because it is under-explored and new regional species continue to be documented.
In the Rio Grande Valley, lichen is abundant on mesquite branches especially, because the trees grow slowly, have stable bark, and are exposed to our high humidity and warm air.
Lichen is a harmless partnership of fungus and algae that uses tree bark only as a surface to sit on, getting its food from the air and sunlight rather than harming the tree, although its presence may point to an unhealthy or dying tree caused by other reasons.
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