No matter where or when you fish for freshwater species, in streams or still waters, you can be sure that one order of aquatic insect is present on the menu of any kind of fish you hope to catch. Most fly fishers chase the glamour hatches — mayflies, caddisflies, and stoneflies — but in doing so, they tend to forget about the most reliable hatch of all: midges (the Chironomidae family) and mosquitoes (the Culicidae family) in the order Diptera. These two aquatic insects are found everywhere, throughout the seasons, and tying and fishing representations of their life stages after they emerge from the egg is sure to increase your angling success and pleasure.
Midges and mosquitoes deposit their eggs on the water, but the eggs, which are tiny, are not really a food source for freshwater fish. Midge eggs sink to the bottom, while mosquito eggs remain floating on the surface, where the mosquito hatches from the egg and remains near the surface through all its stages until it emerges as an adult. Both midges and mosquitoes hatch into larvae after one to three days, depending on temperature, and it is the larval stage that is first of interest to fish and therefore to fly fishers.
The Larval Stage
The larval stage is where the principal difference between the midge and the mosquito is found. Midge larvae burrow into the bottom, and for that reason, they are not an always an abundant food source for fish, which makes them only somewhat important to the fly angler. Midge larvae can be imitated with a simple rubber leg (Figure 1) tied on a size 30 to size 14 hook — chironomids are not always tiny. Present this fly dead drifted at the bottom. If under an indicator, the movement of the surface water should provide enough action to make it enticing. Midge larvae vary in size and color, so carry a variety.
Mosquito larvae (wigglers or wrigglers) live in the water, not in the substrate, and have four developmental periods or instars, each larger than the last. At the end of each instar, the larva sheds its skin. The larvae feed on particulate organic material in the water. The larvae of most mosquito species have a breathing tube and must occasionally come to the surface of the water to get oxygen. The total length of time that mosquito larvae spend in the larval stage depends on the species and the water temperature. Some can develop in as little as five or six days. Upon maturity, the fourth instar larva molts into the pupal stage. The flies in Figures 2 and 3 imitate mosquito larvae quite nicely. Fish mosquito larva imitations at the surface. The Parasol Fly (top right) will support itself, but the glass-bead, thread-body imitation needs a greased tippet to support it.
The Pupal Stage
The pupal stage is probably the most popular stage to fish (Figure 4), and a pupa imitation is likely the pattern most often used to represent either the midge or the mosquito. This can be a weighted fly presented on the bottom to imitate the midge pupa beginning to rise to the surface or a floating pattern presented at the surface to imitate either a mosquito pupa or a midge or a mosquito beginning to emerge as an adult. A wide variety of pupa imitations are available; an example of a good choice is the tungsten beadhead Zebra Midge. Fish it a foot or so off the bottom to represent this stage of the midge.
The Emerger Stage
The emerger stage is perhaps the most overlooked, but may be the most productive stage to imitate. The emerging bug is easy prey. Also, an emerger pattern could represent not just a midge or mosquito, but a mayfly such as the Baetis. The emerger stage is where a soft hackle or flymph really shines. Tie on a Syl’s Midge (Figure 5) 12 to 18 inches below a dry fly and fish this combination dead drift. Another option is a soft hackle with a light-colored body to represent an emerging mosquito (or a Pale Morning Dun). Soft-hackle patterns look alive in the water and are very productive.
The Adult Stage
The adult stage of the midge and the adult stage of the mosquito are so similar that one fly pattern imitates both. Although an upwinged dry fly is a fine imitation, it can be frustrating to tie on hook sizes 20 and smaller. Two easier-to-tie patterns, the Renegade (Figure 6) and the Griffiths Gnat (Figure 7), were developed decades ago and are still very effective at drawing hits. Fish them in sizes 10 to 30 on the surface, at rest or with an extremely slow retrieve, just enough to move the fly, exposing it to more fish.
The Anytime, Anywhere Bugs
In its pupal and larval stages, neither the midge nor the mosquito are very good at swimming. However, do not let this lead you into thinking that they are found only in ponds, lakes, or very slow portions of a stream or river. Regardless of the turbulence of a stream or river, there are multiple microenvironments from as small as your fist to as large as a swimming pool suitable for midges or mosquitoes to inhabit. Fish know where these are, and they sometimes will tell you: be observant of rise forms. The place for presenting your imitation is likely going to be in the softer water of a pocket in moving water or wherever you see fish rising in ponds or lakes.
Studies have shown that midges and mosquitoes typically represent about one-third of the insect species in most lakes and streams. One source noted that it’s common to find more than 150 species of these insects in a stream or 50 species in a marsh or small pond. In the 11 midge subfamilies, there are over ten thousand species and subspecies, and in the 19 mosquito subfamilies, there are eighty thousand species and subspecies. Their ability to survive in a wide variety of aquatic and terrestrial habitats makes them the most available food source all year long to the freshwater the fish we seek.
These bugs are everywhere. The larvae of some species have been found in a cryptobiotic state in which measurable metabolic processes stop, enabling them to withstand temperatures from minus 270 °C to plus 102 °C. Some species have a tolerance for high salinity — midge and mosquito families are among the few insects that have adapted to both freshwater and marine environments. Their mouthparts enable them to feed on algae, plant tissue, detritus, wood, sponge, food particles in suspension, the hemolymph of other insects, and even a variety of animals, although only the female mosquito “bites,” and then only when her eggs are developing. They have evolved into mutually beneficial as well as parasitic relationships with other insects, sponges, mussels, turtles, and fishes both in the water and on land.
Simply because these bugs are so available to so many fish species in so many places fish throughout the year, it would be a strategic error to leave for any fly-fishing trip without carrying some midge or mosquito imitations.
