Aquatic Insect Phenomenon

 From the 15th April to 18th April 2023 we experienced an odd insect phenomenon. Each night in the Cairns-Kuranda area we were beset by thousands of aquatic insects of many different kinds attracted to the lights after dark.

Remember to click on the photo to enlarge

There were many kinds of water beetle, mostly small, and many other aquatic insects such as water striders, caddis flies and aquatic flies.

On the night of the 16th April we ventured out to the Petford, Qld, area some 125 km from Kuranda. To our surprise a similar phenomenon was occurring. Within a few minutes the light sheets were covered with aquatic insects, seemingly the same or similar species that we had seen in Kuranda.

Windrows of tiny aquatics accumulated at the lights. They were so dense that we had to place tissue in our ears to prevent to tiny insects from crawling in.

Amongst the insects were species of the family Tetrigidae, Pygmy Grasshoppers. This one is Paratettix femoralis. These small grasshoppers live along watercourses where they feed on algae and diatoms. But why would they fly away from such habitats?

About 10 years ago I had a call from the Cairns Airport. Management was concerned about large numbers of tiny grasshoppers invading the passenger lounges and the potential damage they could cause if they were to be sucked into the jet engines. What to do?

The following day I had business in Atherton and observed large numbers of the same grasshoppers all over buildings and businesses that were lit overnight.

So what is happening here? Who knows, but it seems that when certain atmospheric conditions prevail, and the moon is in the proper phase, something prompts aquatic insects to leave the water and take flight. They are probably searching for other suitable sites. Most probably meet their demise without finding the perfect aquatic habitat. But the large numbers assure that some will be successful.

Within a few days, all returned to normal and not a single aquatic insect was found on my lightsheets.