What Time is it in Nature: Water in Winter
As the weather starts to cool, we will start to see fewer and fewer insects active at Prairie Ridge. Because they are endothermic (“cold blooded”), many insects enter a dormant period during the cold months, often overwintering in some hidden, protected spot as eggs or larvae in a sort of suspended animation until spring or summer. However, there are places on the Prairie Ridge grounds where you can find insects active year-round, where even on the coldest winter day you might still find insects going about their regular business: our stream and pond.
In spite of some of the difficulties that life in water brings for aquatic insects, it’s still a great place to live. Most importantly, water is very thermally stable. It takes a long time for water to heat up and cool down, especially in large quantities. This means that aquatic insects often experience far less fluctuation in temperatures than their land dwelling relatives. Many aquatic insects are also well adapted to living in a cool environment and are quite capable of carrying on with their regular lives in our relatively mild winters. Short of freezing over (and maybe even then!), you will be able to find at least a few insects swimming around in our ponds and stream even on the coldest days of the year.
A trip to the pond and a few sweeps of a net will currently yield a surprising diversity of aquatic insects. Dragonfly nymphs are quite common:
Dragonfly nymph
Many dragonflies overwinter as immatures (nymphs) in the water, so even though you might not see adult dragonflies flying, you can still find lots of nymphs that will emerge as adults next spring or summer. Dragonfly nymphs are wonderful creatures, expert hunters with an amazing extensible mouthpart that they use to reach out, grab, and hold prey while they eat. These highly visual predators are an important part of the pond’s ecosystem.
Another fascinating aquatic insect from the pond is the phantom midge larva:
Phantom midge larva
These will eventually pupate and emerge as flies, but they are spectacular as larvae! Phantom midges are almost completely transparent, a trait that protects them from predators such as fish (though we don’t have fish in the Prairie Ridge pond) and dragonflies and allows them to swim brazenly right out in the open water. When you scoop these up in the net, you can barely see them unless they move, and then only because they carry two internal air bubbles that reflect light. You are unlikely to see a phantom midge larva simply by looking into the water, but there are thousands of them (maybe millions) swimming about in the water in our pond!
A great predator is the creeping water bug:
Creeping water bug nymph
They’re a lot smaller than some of the other predatory insects in our pond, but don’t let their smaller size fool you. These insects are fierce! They have a powerful paralyzing venom that they inject into prey after capture, so these insects can capture and eat things that might seem too big for them to manage. The bite can also be painful to people who come into contact with an unsuspecting creeping water bug. They’re not inclined to bite in general, but will bite to defend themselves from perceived threats, so handle these bugs with care.
These are just a few of the insects active in the water now! You might also find midge larvae, giant water bugs, water scorpions, predaceous diving beetles, water scavenger beetles, mayflies, caddisflies, or other aquatic insects happily swimming about in the water or nestled safely under rocks, not to mention an array of tadpoles, salamanders, snails, worms, and crayfish. It might seem pretty dead on land in the winter, but the aquatic habitats are still going strong and are teeming with life!
Take a look in the pond or flip a few rocks in the stream the next time you visit Prairie Ridge. You might be surprised by what you find!
What Time is it in Nature is a weekly feature highlighting the current plants, animals, and other wildlife at the Musuem’s public outdoor facility, Prairie Ridge Ecostation. Find out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive!
(Photos by Chris Goforth)
NC Museum of Natural Sciences Blogs 
Enjoyed your post this day (as well numerous others in the past). Your photographs just keep getting better and better; I am envious. I have a particular interest in the aquatic ‘bugs’. I have been running a volunteer stream water quality monitoring program in a rural Ohio county for the past 5 years, and examining the critters has become a most enjoyable pastime. Although our climate must be somewhat colder than yours, I too have been able to observe insect activity almost year round under the water surface. We live in a headwater area (highest point in Ohio in fact, at whopping 1550+ ft above sea level). Several of the sites we have under observation are intermittent streams, that are usually dry through the winter. But when conditions cause them to have a flow, almost immediately the little critters can be seen. One of the most fascinating occurrences (for me, anyhow) has been to watch little tube caddisflies (Lepidostomatids) haul themselves around on the bottom, seen through a thin layer of late winter ice. All may dry up the following week, but then when the waters return again…there they are! Tenacious, and amazingly adapted to their environment. Have not seen your phantom midge, you talk about their being found in your pond, perhaps they are not happy in flowing water, as that is where most of our observations take place…or maybe I’m just not that good of an observer.
At this time of year, we are preparing our annual report of our stream findings, which we will present to our sponsor, the county SWCD/NRCS. I am already planning for next year, and waiting for the water to once again flow down the hill.
Thank you for your blog, it is ‘right up my alley’.
George
So glad you enjoyed the post! I’m also thrilled to hear that you are running a volunteer stream monitoring effort. Excellent! We need more people like you in the world. As for the phantom midges, yes, they’re a pond/lake species, so you won’t find them in flowing waters. They’re open lentic water specialists, so you’ll need to look in open areas in a pond or lake in your area to have a chance of seeing them. They’re amazing insects, and pretty much the only insects you’ll find out in the middle of big lakes. Everything else gets massacred by fish, but not the phantom midges!
Very glad to hear that you’ve observed lepidostomatids crawling around under the ice! Wow. Aquatic insects are just so cool. How can you not appreciate exothermic creatures that are still capable of movement at freezing temperatures? It just boggles the mind, yet you see it all the time if you take a moment to look!