Earlier this year I showed the young larvae that depended on their resemblance to bird droppings to avoid being eaten. Larger specimens still bear a bird dropping appearance, but they are much more noticeable and have gained a few additional tricks to avoid being something’s meal. At the slightest disturbance, the enlarged thoracic region of the caterpillar raises to display its mask to a potential predator. A show of eyespots is often an effective way to scare off birds.
A more aggressive disturbance causes the caterpillar to draw its weapon, a projectable organ known as an osmeterium. The osmeterium exudes an unappealing substance that combines touch and smell to deter predators. In cases like this, I usually attack using a stick so as to avoid carrying the odor with me on my fingers.
If the attacker comes from the front, the osmeterium takes on the appearance of a snake’s tongue, another visual deterrent to attack by birds.
This larva is about an inch and a half long. It won’t be long before it moves off to find a suitable place to form a chrysalis, the form in which it will spend the winter. Maybe I’ll see this guy in adult form next spring.
I found several suitable photographic subjects. There are many fluorescent blue spots and streaks that make the caterpillar appear to be throwing electrical sparks. I wonder if those might serve as another warning to potential predators.
A single clump of Prickly Ash contained half a dozen larvae. Most were resting quietly on the stems, but this one was busily consuming a last leaflet.