Poplar Lappet Moths: these moths are able to mimic the dead leaves of a poplar tree (there is at least one moth in each of the photos below)
Above: the photo at the top shows two poplar lappet moths disguised as foliage (the two "leaves" on the left-most end of the branch are actually moths) and the photo on the bottom shows another poplar lappet moth clinging to a leaf
The scientific name of this species is Gastropacha populifolia, but it's more commonly referred to as the poplar lappet moth. It's also known as pappelglucke in German and feuille-morte du peuplier in French.
The moths are distributed across large sections of Europe, Russia, China, Korea, and Japan, but they're regarded as a rare species throughout most of Europe.
The shape, color, wing pattern, and resting position of this species all contribute to its unique disguise, as it bears an uncanny resemblance to a dead leaf. It even has a dark, snout-like projection (the labial palpi) that mimics the stem of a leaf, and its wing pattern completes the illusion with a dark, raised line forming the central "vein" of the leaf; the soft ridges and scalloped edges of its wings also add to the effect.
There are many other leaf-mimicking moths out there, but this species is particularly impressive.
The caterpillars also have a knack for blending in -- thanks to their cryptic coloration and fuzzy, setae-lined sides, they are easily camouflaged against the bark of a poplar tree.
Above: the photos at the top show Gastropacha populifolia caterpillars blending in by pressing their bodies flat up against twigs/branches, and the photo at the bottom shows one of the caterpillars in a more conspicuous setting
These moths are defended by more than just mimicry, though; they can also produce ultrasonic clicks that interfere with the echolocation signals of predatory bats, which allows the moths to avoid being detected (and ultimately eaten) by bats.
Above: the adorable face of a poplar lappet moth
Nota Lepidopterologica: Continuous Long-Term Monitoring of Daily Foraging Patterns in Three Species of Lappet Moth Caterpillars
Catalogue of the Lepidoptera of Belgium: Gastropacha populifolia
Moths and How to Rear Them: Gastropacha populifolia
Wikipedia (German): Pappelglucke
Moths and Butterflies of Europe and North Africa: G. populifolia
EurekaMag: Effect of the Scale Coverage of the Moth Gastropacha populifolia on the Reflection of Bat Echolocation Signals
