Crawlies with Cri: Flat bug

Flat bug (Aradidae)

This week’s crawly is so flat!
How flat is it?
It’s so flat they just named it the “flat bug” (Aradidae).
I mean, there are 10,200 species of true bugs (Heteroptera) in North America, and they named this one, single family flat bugs. Your flatness really must stand out to get a special moniker in a sea of 10,200 other bugs.
Our featured species Aradus fuscomaculatus is one of 130 species of flat bugs found in North America, and they are only found on the Pacific Coast. They are associated with fir, spruce and oak trees.
But don’t panic.
Flat bugs don’t harm trees. In fact, flat bugs don’t harm anything. They’re so unremarkable in their harmlessness that we know very little about them.
In entomology as in life the “squeaky wheel” gets the grease. That is, the pestier a crawly, the more we seem to know about them.
This may also be why flat bugs are simply called “flat bugs” while the Asian giant hornets got themselves nicknamed “Murder Hornets” for a short bit because everyone freaked out over them initially.
To be fair, the flat bugs’ lack of pestiness isn’t the only reason they haven’t been extensively studied. They’re also darn hard to find.
Flat bugs are flat for a reason. Their diet consists of fungus growing under the bark of decaying trees. Now you see why they are so flat; there isn’t much room between a tree trunk and its bark.
They will also wander around on top of tree bark eating fungus, but you can easily see their camo coloration and pattern – along with their diminutive just-under-one-quarter-of-an-inch size – make them blend in flawlessly on tree bark.
But wait, there’s more! Their textured exoskeletons are perfect for picking up detritus as they wander, so they are also often covered in bits of fungi, bark, lichen, dirt, etc.
In case all those hiding/blending tricks weren’t enough, flat bugs also move at a snail’s pace. While they do have wings and can fly, they generally just meander from one yummy bark-covered fungus patch to another.
Luckily for me, none of these clever camo techniques work well on a slightly mossy white deck railing, or I’d never have spotted our pictured flat bug.
Not only are flat bugs not harmful, they happen to be beneficial. They intake fungi, but their “output” as it were helps to improve soils. No doubt they’re also food for very industrious birds and other arthropods who can find them.
They’re efficient too. I’ve mentioned their slow movement; they’re masters of conserving energy, but they also have a neat trick for finding food. Flat bugs are attracted to bark beetle pheromones which leave a nice trail right to the Flat Bug Buffet of Fungi. Why bust out a map, or worse, stop and ask for directions, when there’s free olfactory GPS available?
Speaking of the fungi buffet, how do flat bugs eat? Like all true bugs, they have stylets, which are piercing, sipping mouthparts – built in head straws if you will.
In the case of flat bugs, they’re the “Krazy Straws” of stylets. They’re super long, and flat bugs keep them neatly coiled in a special area inside and at the back of their wee heads when they aren’t actively eating.
Nature never runs out of creativity!