The meteoric rise, fall, and rise again of the semelparous mosquitoes is a series of extremes unmatched by any other clade on Apterra. After achieving immense success in the earliest days Post-Abandonment, Aedes semelparosus fell into obscurity when other insects overtook them as the planet's dominant flying animals. With the innovation of a fully-aquatic life cycle, their descendants now once again find themselves becoming key players in almost every environment. Their evolution over the past 1,500,000 years has been defined by the adult traits they've lost and, in some cases, regained. The genetic hormone imbalance that initially resulted in the emergence of the first neotenic mosquitoes has been refined over the generations, with different subgroups adapting different morphologies that often contain a chimeric mixture of immature and adult body parts.

Not all species of juvenilized flies have become such strange creatures. Gillywogs (Semperinfantidae) still have the appearance of regular-looking mosquito larvae. Blending into the shoals of their more typical relatives, they find safety in numbers. Some, like the Butcherwog (Mendacioculex) are even hunters themselves, taking advantage of the naive offspring of other species. The widespread Cowardly Gillywog (Celariculex) synchronizes its reproductive cycle with the breeding season of local sedentary species in hopes that aquatic predators will ignore the far-less-numerous newborn gillywogs in favor of the abundant targets of their mimicry. This, however, means they'll have to compete for food against the other species. The Lonesome Gillywog (Telmaculex) takes the opposite approach; it spawns when few other larvae are present. This ensures their young will find plenty of detritus to eat, in exchange for increased danger from insectivores. All gillywogs must remain at the surface to breathe through their siphon, while most other neotenic groups have evolved to get their full oxygen requirements through their gills.

Tailtube Worms (Ichthyoculicidae) are another family that remain more-or-less normal in their basic body plan. These were the first neotenic mosquitoes that evolved to withstand saltwater, and they're commonly found in oceans, lakes, and rivers. They are especially prevalent anywhere with fast-moving currents, as their gillywog cousins are too slow-moving to survive in such habitats. Tailtubes, on the other hand, are powerful swimmers. The siphon (which is no longer used for respiration) and gills of their ancestors' tails have been reshaped into the upper and lower halves of a forked fin, while the body segments are smooth and streamlined. Though still not as fast as most fish, they can hold their own against other invertebrates of a similar size, such as the slow-swimming subfluvial isopods that share their waterways. With their omnivorous diets, they are equally comfortable consuming algae, copepods, water fleas, and even small fish fry, whose parents in turn feed on the tailtubes. A notable feature of this family is that, since their gills are used for propulsion, oxygenation increases as they swim faster. This grants them great endurance but also means that they cannot ever completely stop moving. If they do, death is certain as oxygen will cease to flow across the gills entirely, causing rapid suffocation.

One step further into the territory of odd and derived body plans lie the Leechelets (Hirudomimidae). Their bodies are largely similar to those of gillywogs, but their faces closely resemble those of an adult mosquito. This is caused by further changes to the mutant gene variant that originally caused neoteny to emerge. This gene suppressed the production of pupation-inducing hormones in body tissues, but still allowed the gonads to develop to maturity after the last molt. In leechelets, the gene is also inactive in the face, causing the growth of a fully-formed proboscis instead of the unspecialized jaws common in most neotenics. Large fish are their primary targets and generally make for easy hosts, as they lack the ability to groom themselves of these clinging parasites. Unlike their flying ancestors, leechlelets may feed for many hours at a time. Some members of this family have reverted to a semelparous life cycle. For example, the type genus Hirudomimus feeds once, mates, spawns, and dies within a matter of days after reaching adulthood. Its cousin Incursoculex, commonly known as the Fleshboring Leechelet, has a very different strategy. It never detaches from its host at all, remaining embedded in the fish's flesh for its entire life, which may be as long as four years.

Scuttleworms (Vermitarsidae) have regained the function of their legs, which they use to crawl across murky lakebeds and cling to slippery river rocks. Many are ambush predators, such as Culicaris, a crayfish-like mud-dweller that preys on minnows, isopods, and other insects. Others are more peaceful, like the herbivorous Canistroculex, which grazes on freshwater seabasket-relatives across northern Abeli. These are among the largest of all Aperran insects, reaching fifteen centimeters in length and more than twenty in legspan. 

The Airgills (Spriaculobranchidae) have the strangest lifestyle of any mosquito so far. Possessing a set of air-breathing respiratory spiracles in addition to their functional siphon and larval gills, they are capable of breathing both in and out of water. As such, they've colonized all of Panapterra, crossing between disconnected bodies of water in a fashion none of their relatives are capable of. A few species even spend the majority of their time on land, burrowing deep into the soil in search of moisture. As they build their tunnels, they aerate the earth, promoting the growth of plants above them.