I had to create two presentations from scratch for this week. It’s rare that I build a presentation from scratch anymore, let alone two in one week. Usually, I can adapt one of the countless presentations I’ve built over the last 25 years or so. As a result, I’d kind of forgotten how much time it takes… Don’t worry, I managed to get them both done.
For one of this week’s presentations, I was asked to talk about how insects camouflage themselves. I decided to interpret that broadly and include other arthropods, and I also decided to include other ways of hiding or concealing that might not be strictly considered camouflage. Here is a short sample of the much longer presentation I’m giving on Friday.
When I think of camouflage, I usually picture something that conceals a creature (or object) by making it blend into its surroundings. The moth in the above photo is a great example of that. If I hadn’t seen the moth move, I never would have spotted it. Another example I see a lot in Nebraska prairies is the cudweed grasshopper (Hypochlora alba), which conveniently matches the color and pattern of the leaves on its favorite food – cudweed sagewort, aka white sage (Artemisia ludoviciana). When I’m leading tours, I pay close attention as I walk through patches of sagewort, looking for the pale insects jumping away from my feet. Then I try to grab one, along with a sample of the plant, to show people its supremely effective camouflage.
Sometimes invertebrates escape notice simply by sitting very still. Movement is what most easily catches the eye of potential predators or prey, so even if a creature doesn’t particularly match the background, sitting very still can be effective. Of course, if you can do both (match background AND sit still), as many crab spiders can, that’s even better. Some crab spiders can even change their color from white to yellow – or vice versa – to expand the range of flowers they can hide on as they wait in ambush for prey to come near.
As many (human) hunters know, sometimes it’s not as important to match the color of your surroundings as it is to break up the outline of your form. Camouflaged clothing works because it obscures the shape of the body wearing it with crazy-looking patterns. Similarly, many insects and other small creatures have texture or color patterns that break up their form. Ambush bugs, with their odd squat shape and textured back, are a good example of this, and they seem to have no problem catching prey on flowers, even if they aren’t the same color as the flower itself.
Another example of an insect with a strong camouflaged pattern is the painted grasshopper (Dactylotum bicolor). Somewhat like a zebra, it has a color pattern that is both showy and concealing at the same time. The grasshopper, however, goes beyond the showiness of a zebra, by adding bright colors (usually red or orange around here). That coloration may also fend off potential predators who are programmed to be wary of bright red or orange insects because many have a bad taste. Regardless, when a painted grasshopper is sitting still in a dry grassland, its pattern makes it very hard to see, despite its gaudy appearance.
Some invertebrates go beyond trying to conceal themselves in plain site and either use or create physical hideouts. One common example is the fly that lays eggs on a goldenrod stem, causing the stem to swell up and form a ‘gall’ when the fly larva burrows into it. The fly then grows up inside the gall, overwinters in the insulated and (relatively) safe space, and emerges as an adult in the spring.
Many spiders and moth larvae (both of which can produce silken strings) use silk to sew leaves or flower petals together to create hiding places. Sometimes they use that strategy to conceal themselves while they eat a flower. Other times, they simply need a safe place to spend the winter or otherwise pass the time in relative safety.
A last way (that I’m covering here) invertebrates can hide is by pretending to be something they aren’t. There are lots of examples of invertebrates that look like leaves, plant stems, even bird droppings. They can sure fool you and me, and I assume the strategy works on many of their potential predators as well.
Alternatively, some small creatures mimic the appearance of others. There are robber flies that look nearly identical to bumble bees, for example, which can fool their prey into assuming they’re harmless. Another of my favorites is the wasp mantidfly, which is a predator with praying mantis-like front legs on a body that looks very much like a paper wasp.
These are just a few samples from my 30 minute presentation, which gives you a feel for how many examples of invertebrate concealment there are. Plus, I’m only going to be talking about the ones I’ve actually photographed, which leaves an awful lot out.
Here in Nebraska, and in many other places, we’ve reached the end of this year’s growing season and invertebrates have largely disappeared from the prairie. Most of them aren’t really gone, though. Instead, they’re out there hiding in the vegetation or soil somewhere until it’s time to emerge again – and immediately try to hide in other ways – next spring.