Giant Stick Insect & Flying Caterpillar Frass - Slow Mo

[00:00:00]This video has two spectacular things in it,  one is this: one of the biggest insects I’ve ever filmed, a stick insect taking flight. The other is this, the backend of a butterfly caterpillar balistically ejecting  frass (aka insect poop). I’ll show you what this looks like and how it works  in gloriously-detailed slow-motion footage.

[00:00:22]So, normally, I spend my time filming and  studying insects local to here in North Carolina.

[00:00:27]But what those two things have in common is  that they are exotic lab-reared specimens.

[00:00:32]To film them I worked behind the scenes here at  my museum and in a lab at Middleburry College in Vermont. Let’s start here at the museum. The stick insects are exhibit animals kept and breed behind the scenes here for showcasing in our  arthropod zoo. This species, sometimes called the spiny leaf insect or giant prickly stick insect,  is native to Australia but is kept in captivity all across the world. The females of this species,  like you see here, are larger and flightless. And here you’re seeing one with a male clinging to her  back to for a size comparison. Males are slender with long wings and fewer spines on their body. To get shots of the males in flight, they needed a little encouragement and direction once they  were on the filming set. Any stick insect’s first response to an unfamiliar touch, like what I’m  doing with a paintbrush, is to stay in place and gently wiggle like it’s a piece of vegetation  moving in the wind. For these males when that move didn’t fake me out and they kept getting  touched with the brush, they eventually would leap into a short flight off the platform and I’d  have my shot. Even these big insects flap their wings pretty rapidly so the shots you’re about  to see I captured at 1,500 frames per second.

[00:01:43]So, here’s these shots. This is the first time,  I’ve captured this order of insects in flight.

[00:02:01]This is the second of three clips I  captured and I think the main thing to get out of all of these is just a sense of  awe and wonder for what these insects are. So, I’m gonna get my narration out of the way  and we can watch this footage together.

[00:02:51]Ok, so now lets switch to another insect. This  is the adult stage of the squinting bush brown butterfly. It’s a nymphalid that’s native to  the eastern part of Africa. But, it’s also found in labs all across the world, as it’s studied  as a model system for all sorts of biological questions. One of the reasons it works well in  labs is because it has a short generation time and can be raised on easily-grown grasses. In the  lab where I filmed these in, in Vermont, they were raising them, like this, on lab-grown corn plants. So, as caterpillars, they are constantly eating.

[00:03:24]And if you’re eating a lot you’re also going  to be producing a lot of waste. Waste for these and most other caterpillars comes out as  a solid pellet referred to as frass. These frass pellets can be quite big for some caterpillars,  littering the forest floor around feeding spots.

[00:03:40]With the caterpillars I filmed, instead of  just dropping their frass pellets right from where they feed, they forcefully fire and  fling their frass away from themselves.

[00:03:49]Why exactly these ones do it is  unknown, but for others they fire their frass to avoid amassing chemical  cues that predators could hone in on, and possibly also for hygienic  purposes to avoid attracting disease.

[00:04:02]How they do it is by building up pressure as they  expel the frass pellet. You can see that happening in this footage as the back of the caterpillar  inflates once the pellet is in firing position.

[00:04:13]Comb-like structures work as a latch holding  the pressure in. When they release, these combs fling against the frass pellet flipping it away  and making it rotate end-over end as it goes.

[00:04:25]These pellets are traveling at just under  1 meter per second. I didn’t get to measure how far they flew, but in other species they can  go up to 80 cm and around 40 body lengths away, which is pretty impressive.

[00:04:39]Ok, I have one extra thing to show you  about flying caterpillar frass. But, this isn’t about a moth or a butterfly it’s a beetle. This is a Warty Leaf Beetle, it’s one of hundreds of species in this group and most of them,  as adults, are visual mimics of caterpillar frass pellets. Which also indicates just how  common-place frass pellets are. On vegetation, they are slow moving and convincing.  But the mimicry gets even better when they are disturbed because they tuck in  all their appendages and become the fully rounded shape of an actual fecal pellet. Of course, if things get really bad for these beetles, they can drop the mimicry act  and use their wings to takeoff and fly away.

[00:05:17]So, it’s likely that during random parts of  the day in the forest there are both actual frass pellets and frass-pellet-like beetles  flying through the air at the same time.

[00:05:28]OK, that’s all the flying stick insects and flying  frass footage I have for now. Thanks for watching.