Wednesday, June 11, 2014

Bug of the Week

Time for the return of an old favorite - our occasional 'bug of the week' post....

Back in early March, I was strolling through the fields at Higbee Beach WMA when a bundle of dead leaves caught my eye. Nothing so unusual about that you might think, but eye-brain co-ordination is an intriguing thing and some deep-seated search image was trying to push its way to the front of my conscious mind. I walked into the vegetation a few paces and the bundle of leaves took on clearer features - the leaves were all pulled together and bound up with silken threads. This was clearly some sort of coccoon but no ordinary coccoon as this baby was some four inches long!! A quick check around the outside revealed no exit hole and a little shake revealed that there was still a chunky object inside - the chrysalis of a moth, and a big one at that!

The cocoons of the Saturniid moths are mostly designed to look like something that would be of no interest at all to anything predatory - and a bundle of old leaves serves the purpose just grand [photo by Mike Crewe].

Knowing that it was the perfect time of year for the meadows to be cut to help deter invasive plants and promote native species, I feared for the survival of this coccoon. While caterillars can crawl and adult moths can fly, the pupation stage of a moth is a real weak link in the life cycle. While the caterpillar metamorphoses into a moth, it can do nothing but hope; hope that it has chosen a safe, protected place to hang out for the duration, and hope that its camouflage fools potential predators. For many moth species, pupation takes all winter, so there is plenty of opportunity to be found out. The one I had spotted was just six inches or so off the ground, attached to a small sumac sprig and clearly right in harm's way. I broke off the twig below the coccoon and took it home, propping it upright in a small pet container that I keep for just such occasions.

The days, weeks, even months went by; the box sat on top of the tumble drier in the utility room, frequently being moved back and forth as equipment was needed. It was checked daily for a while, then weekly, then, well, you know, nothing was happening. It got forgotten...

Forgotten that is until my wife presented me with it one day and there, quite freshly emerged was a spectacular female Cecropia Moth - our largest moth species. Though we had missed the emergence of the strangely yukky-looking creature that presents itself before the wings have been pumped up, the tips of the wings were still a little soft and floppy, so it had only emerged within the hour. What it must be like to go through a complete metamorphosis and just how much the creature is aware of is something we can only ponder on, but it is certainly a remarkably complex process and one we shall - thankfully - never have to experience!! We released our moth at dusk (when there is a greatly reduced chance of a bird making off with it) into the back garden, resting her on a tree trunk from where she could head out in her own time.

The vibrant colors and spectacular size of our freshly-emerged female Cecropia Moth. Eye spots are common features of moth wings and appear to serve as startling mechanisms for would-be predators. Some researchers also think that the curved and rounded wing tip of a number of Saturniid moths may even be mistaken for a snake head [photo by Mike Crewe].