Dipterachnids (family Arachnoculicidae) comprise the hyper-diverse descendants of the dipterantula harpoonjaws that lived during Apterra's previous age. Their entire history, from their origins at the tail end of the Ice Age, has been one uninterrupted adaptive radiation, leading to more than three thousand species living all over the world today. They owe their success to the fact that Apterra began with no terrestrial arthropod predators to speak of; before the evolution of the first dipterantulas, the only major threats to insects and crustaceans on land were tetrapods, Pugilops, and carnivorous plants. In the past few million years, Dipterachnids have joined these organisms as major predators of any animal smaller than ten grams or so.
Not all dipterachnid wings are entirely useless for aerodynamic purposes. One subfamily, the Flapaways (Retropterinae), can quickly but clumsily flutter short distances, a trait they've secondarily re-evolved from truly flightless ancestors. Members of this clade specialize in hunting social prey, picking off individuals from the outskirts of the group. Unfortunately, after a few thousand generations of this, group-living arthropods like arboreal woodlice adapted defensive strategies, fiercely attacking when they noticed one of their number had been grabbed. In response, the atrophied flight muscles of ancestral flapaways have become functional once again, allowing their owner to quickly snatch a vulnerable target, take off backwards, and escape before the victim's compatriots can mount a defense.
One other subfamily, along with the flapaways, forms a clade called the Symmetriopterians, sister to the rest of the dipterachnids. This group - called the Squirewings (Thyreopterinae) - may seem at first glance to be nothing like their closest relatives. The wings of Thyreopterines are completely immobile, fused to the surface of the thorax and abdomen. The connection between the middle and rear sections of the body is very broad and smooth, leading to the appearance of an opisthosoma hidden beneath the forewings. Plates of highly sclerotized exoskeleton cover the rear two-thirds of the body, and even the face bears a hard frontal shield. This level of fusion means the entire body aside from the head and legs is functionally a single rigid structure, unable to flex more than a few degrees vertically or horizontally. Such sacrifices were necessary when the ancestors of squirewings first began to specialize in hunting castlebugs and other well-armored prey. Their strategy, like that of all dipterachnids, begins with an ambush attack. But while other subfamilies try to inject a dose of venom immediately after they make contact, this is rarely possible when hunting castlebugs, as their armor overlaps nearly all their joints, preventing squirewings from accessing the soft flesh between the plates. Instead, this clade has developed fangs capable of piercing directly through their prey's hard exoskeleton. These maxillary mouthparts, though derived from what were originally flexible structures, have become calcified and permeated with a tough protein matrix, capped with the microscopic barbs typical of dipterachnids. However, these toughened maxillae are also brittle, so the woodlouse has to be immobilized to ensure it doesn't snap the squirewing's fangs off before the venom does its work. To accomplish this, a squirewing must hold its prey with force, climbing on top of it and using its legs to pin the castlebug down. The Thyreopterine underbelly is hard but still flexible enough to be more or less immune to piercing damage, deforming around the dorsal spikes of the isopod as it squirms until it wears itself out. Only then does the squirewing inject the venom that renders its prey's insides edible.
The next-most-basal Arachnoculicid clade is the subfamily Dextropterinae, also known as Grabwings. This group mostly hunts flying prey, ranging from dustflies to locust reapers to songbugs. Grabwing wings have a long, forward-curving costal margin, functioning like another pair of mouthparts and used primarily for holding onto and pulling down their fluttering prey. This frees up the maxillae to perform the all-important job of channeling Flagelloculicin into the insect's body cavity, after which the labrum and mandibles work together to lap up the resulting organic slurry. While the wings of the some early-branching Dextropterines are symmetrical, the derived members have all modified theirs into a crustacean-like pincer, with the smaller and more mobile left wing designed to pin prey against the robust right wing. Next, once the maxillae have gotten ahold of the fly's body, the pincer jerks upward with the goal of tearing off whatever part of their target is caught within them, usually one of its own wings. This eliminates the possibility of the insect escaping and flying far away before the grabwing's venom can kill it.
All other dipterachnids are known as Sinistropterians, as in this group the left wing sits atop the right one at rest. Some Sinistropterian subfamilies have no further asymmetry, with two wings being otherwise identical. One such group is the Oscillopterinae, or Shield-Wavers, whose wings are as armored as squirewing bellies and attached by flexible, protruding joints, allowing them to swivel above, below, or in front of the body This means they can protect their much softer bodies when hunting prey that's likely to fight back, like large Pugilopsids, locust reapers, and even some vertebrates. Shield-wavers are notably dominant on Aglirium, where terrestrial vertebrates smaller than the smallest kiwis and rats are common. Certain rat pups can also be easy prey, but shield-wavers have low odds against birds, as beaks are generally very effective at targeting the vulnerable wing-base joints. Most Panapterran Oscillopterines focus on killing their fellow predatory insects, sometimes including other dipterachnids, whose venom they are not immune to. It is during these battles when the shield-waver wings are at their most useful, dancing back and forth to block their foe's fangs wherever they may attempt to strike.
Flytrapflies (Viatoropterinae) are another widespread Sinistropterian subfamily, one whose asymmetry is critical to its hunting strategy. Like grabwings, they mainly hunt species that can fly away, but they make no attempt to keep their target on the ground. Instead, their serrated wings turn forward 180 degrees to hold on tight to a leg or antenna as both predator and prey leave the ground. The toothed wing margins interlock, making the flytrapfly nearly impossible to remove. Once airborne, a quick bite injects only a small amount of venom. This means the flying insect's body will shut down gradually, giving it time to find a safe place to land as it feels its muscles growing weaker. The flytrapfly can then eat peacefully while surveying its new surroundings. Some species only hunt prey that flies short distances, ensuring they can always find their way back to a home territory, but others embrace this new method of dispersal, riding prey like dustflies for hours before delivering the killing bite. Flytrapflies are thus the only truly cosmopolitan Arachnoculicids, with many found on isolated landmasses they reached by clinging to far-flying insects like culicondors.