Backyard Nature: Water striders chat, caterpillars attack, and bullfrogs duel

by Marlene Berlin

In Rock Creek Park and along its tributaries, you can see some fascinating critter behavior if you keep your eyes searching – and your curiosity on high alert.

Recently I saw what appeared to be ripples in Rock Creek from droplets of water landing from above. But it was not raining, and it had not even rained the night before. Then I wondered: Could this be water striders skipping about?

As the video below explains, water striders (also known as water skimmers, pond skaters and water bugs) create water ripples as a form of communication for mating and establishing territory. They can also “read” ripples created by prey.

A combination of surface tension, long legs and water-repellent hairs lining their bodies allow water striders to stay afloat. They feed on bugs caught in the water by injecting their prey with a chemical that dissolves the innards. They then slurp ’em up.

Nature vs. Nature, round 2

While walking through Linnean Park a few days later, I saw silk webbing wrapped around two sections of a branch.

Inside were tiny cream-colored worms or larvae wriggling around. Then I noticed a much larger creature inside: a wasp trying to get away from young caterpillars on the attack.

The light color of the caterpillars signifies that they recently hatched from the eggs laid by a moth, most likely the forest tent caterpillar moth. I had heard of tiny parasitic wasps that lay eggs inside of the living caterpillars, but I was left to wonder why a full-grown wasp would go inside the tent. Let us know if you have any ideas.

Man vs. Nature

Water striders and forest tent caterpillars are native to the area. Some of the vines and other growing things that have taken up residence in our local parks are not. On the day I witnessed the caterpillars attacking the wasp, I encountered one of Linnean Park’s volunteer caretakers attacking vines choking the life out of young trees. John Burwell, a certified Weed Warrior who also leads volunteers in removing invasive plants, was out on his daily rounds.

Frog vs. Frog

Last Friday, I was out at the Tregaran Conservancy frog pond. I had high hopes of hearing a robust chorus of bullfrogs. That was not to be. But I did witness a duel.

As I sat and watched, the frogs started gliding toward one another. When they met, they attacked.

Then one disappeared and the one remaining bullfrog glided to the center of the pond. Was he declaring himself king of the pond?

Wasp vs. Wasp

The bullfrogs’ fight was not the only one I witnessed that day. On my walk back from the Tregaron frog pond, I spotted common wasps battling with bald-faced hornets (another type of wasp) in the hollowed out base of a tree.

Nature is not always pretty or peaceful. But it is always fascinating to watch.