Insects of the Late Thermocene
The tropical conditions of the past one hundred million years have been highly suitable for the survival of cold-blooded animals, not only fishes but also invertebrates.
Insects of the late Thermocene are a curious mixture of very modern forms and extremely derived groups very far removed from their ancestors. Ants, of course, are highly successful. In addition to the successful colonial forms which remain extremely successful, they have also radiated into numerous cosmopolitan lineages of flying insects, many no longer eusocial and some barely even recognizable as ants; groups have developed which may more closely resemble bees, wasps, dragonflies, mosquitoes, and even moths. They may provide active care and deliver food for their offspring or simply lay their eggs in places rich enough in resources that they can feed themselves once they hatch, such as in carcasses, rotting fruit or the dung of large animals; the larvae of some have even become aquatic. Early flying ants were Serina's first major pollinators and continue to fulfill this role more prominently out all of Serina's animals, but the herbivorous descendants of ladybird beetles and crickets too have produced flying lineages which may feed exclusively on flower nectar. The latter, known as florgusts, are particularly noticeable due to their large and usually brightly colored wings. Florgusts of the Thermocene have spread across the planet. As juveniles they are still very cricket-like, but after molting into adults they lose their jaws in all but a very few primitive species and must feed on flower nectar to survive. On the polar opposite of the morphology spectrum are grapplebugs, predatory crickets which catch prey in spiked forearms like a praying mantis. Often highly camouflaged, they lie in wait and strike at a speed so fast that the prey has very little time to react. Similar methods of hunting have also appeared in the beetles and multiple times in ants.
Bird-eaters
Though insects make up much of the diet of many birds, a select few insects turn the tables and specialize on hunting birds. Hugger wasps, actually multiple species of colonial vesper - flying ant - which can be found throughout the tropics, exhibit behavior far more grim than their name might suggest. Though no larger than a honeybee, through cooperation they can target prey many times larger than any of the ants could individually. Their preferred victims are small sparrow-like birds which do not flock in large groups. By targeting the birds as a swarm, and in particular crowding over its head to blind it and bring it to the ground, they can overwhelm their prey's ability to defend itself and kill it with dozens of venomous stings. Once dispatched, the prey is dismembered and the scraps of meat brought home to feed the wasps' young.
Cradle-robbers are large solitary vespers able to grow up to three inches long, which feed mostly on birds' eggs and their unfledged young. Males, much smaller than their partners, eat mostly other insects, but the bigger female harasses nesting songbirds off their clutches with aggressive diving behaviors and bites to the back and rump. Once she has flown, the robber makes off with an egg or a living chick. A chick is easily taken apart by her strong jaws, but an egg requires more effort to break open; usually, she drops it from a height and then laps up the resulting spilled material.
Many other predatory insects may also consume birds if the occasion arises, even if they do not eat predominately birds. Though grapplebugs eat mainly other insects, the largest species occasionally kill songbirds. Burying carrion beetles introduced to Serina were quick to expand their diets away from carcasses to living prey and gave rise to many flightless predators, both fast-running pursuit hunters which chase down and kill their food on foot to sedentary ambush predators. Though most examples of both lineages are modest in size some can become remarkably large, six or seven inches long or even larger. Usually it is other insects on the menu, though bird chicks - and the adults of small songbirds - as well as tribbets will all be taken readily by the largest carnivores as well. The five inch-long pouncer beetle earns its name from its elongated hind legs, which are folded when running but can be extended to allow it to suddenly spring forward upon its prey once it has gotten close enough; pouncer beetles can even catch birds in flight this way. One of the largest predator beetles of all is the beartrap beetle, as large as a lab rat, which hides in the soil along the trails used by small jungle animals of all sorts, reaching out and grabbing hold of their prey in a set of giant spiked jaws as it passes and dragging it down into a burrow to feed, much like an arthropod crocodile. And of course, we have already been introduced to the predatory burrowing cricket, a major predator of all small burrowing animals, both vertebrates and invertebrates.
Lastly, not all insects which feed on birds necessarily kill their prey. Blood-sucking is common in Serina's derived flying ants, and to breed, some species both of ant and of burying beetles have have become macabre parasites that lay their eggs in wounds and let their larvae feed in the living animal's body. Some beetles take this to an even more morbid extent and create a fresh bite wound into the flesh of a healthy bird and deposit their eggs inside. The wound quickly heals over, but the larvae soon hatch and feed on the living tissue until they mature and burrow their way back out. Nonetheless, some still prefer to get their young off to a good start with a meal which is already dead. With powerful wings and good stamina, females of some species fly great distances in search of carcasses in which to lay their eggs, guided by a strong sense of smell.