Thorn Mimics & Other Freaks of Nature

A thorn-mimicking treehopper on a branch (Membracidae).

Membracids (commonly called treehoppers) are one of my favorite bugs–and one of the few smaller insects that I will consistently take the trouble of snagging for my collection.  At the start of my journey into entomology I can recall being deeply impressed by some thorn-mimicking treehoppers pointed out to me on a branch.  They look like thorns!  They run around the branch and try to hide from you!  They hop!  What’s not to love?

Oh, and a good number of membracid nymphs have mohawks.  That’s pretty freaking adorable, right there.

These little guys are incredibly diverse.  Here’s a picture that’s not mine:

Variation in treehopper morphology (Photo credit: Prud’homme et al 2011).

Not only are there thorn-mimics and brightly colored aposematic hoppers, but also feces and even ant-mimics.  The treehoppers that look as if they have sprouted entire mutant ants from their back are some of my favorites.

Now, I was taught that this structural diversity came from variations in the pronotum, but it turns out membracids are even more interesting than that.  Recent research has provided evidence that the helmet structure is actually a novel appendage, entirely unique to the genus.  This structure is apparently something like a modified third wing, the presence of which may be a result of mutations to the Hox gene complex.   (This is the same group of regulatory/developmental genes that can cause mutant flies to sprout legs in the place of antennae and such.)  A very cool example of evolution in action!

See also: Ants & Hoppers

Ants and Hoppers

Carpenter ants tending hopper nymphs in Argentina.

Since we had the spittlebug nymphs earlier this week, I thought I’d take the opportunity to post a picture of some other hopper nymphs.  These little guys are being watched over by several carpenter ant workers, who will collect their sugary excretions and protect them from predators.

A casual observer might confuse these with mealybugs due to their white, somewhat waxy appearance and their location feeding en masse on a plant stem.  (This casual observer would in no way be me.  Nope.)  However mealybugs, like scales, have reduced appendages and secondarily lost wings.  A close look at these guys will reveal not only well developed legs peeking out, but the presence of small, developing wing buds on their backs, indicating that they are late stage nymphs (immature insects).  In fact, that dark shape near the middle left of the mass appears to be an adult thorn-mimicking treehopper, making it likely that these are members of the auchenorrhynchan family Membracidae.