Tuesday, August 26, 2008


The Dogday Harvestfly (Tibicen canicularis) goes through incomplete metamorphosis, having only three stages in its life cycle: egg, nymph and adult. The nymphs live underground sucking juices from tree roots, preferably pine trees.

After three years the nymphs emerge and go through their final molt, changing into winged adults. The cast off exoskeleton may be seen in the picture below. As is the case with many insects the adult cicada does not eat; it lives long enough to reproduce and then dies.

It's going to take a bit of luck to get a shot of an adult cicada as they tend to spend their time high up in the trees.

Dragonflies also go through incomplete metamorphosis, spending the second stage of their life living a predatory aquatic existence. This discarded nymphal exoskeleton (exuviae) is about 2½ inches long and likely belonged to a skimmer or a darner.

The Monarch Butterfly (Danaus plexippus) goes through complete metamorphosis ... egg, larva, pupa and adult. The larva in following image is feeding on Swamp Milkweed and this one seemed to have a marked preference for the seed pods. The caterpillar ingests toxins present in the sap of the milkweed plant and the bold colors advertise its poisonous nature.

I'm going to be keeping an eye out because this caterpillar looks like it will be ready to pupate any day and this looks like a good opportunity to make a photo essay of the change from larva to adult.

These are the seed pods the caterpillar ate in only two days ...

... and it's moved on to the leaves and still going strong!

Unless I find another caterpillar it looks this photo study of a larva metamorphosing into an adult Monarch won't be finished.

I checked out the caterpillar the following morning; it was torpid and looked like it was ready to pupate. Two hours later ... it was gone. Maybe a bird got it. Birds have to learn to avoid the warning colors and it seems like one might have tested its luck.