Planet of the Bugs: Evolution and the Rise of Insects (20 page)

During the Permian years, insects suffered their most catastrophic setback of all time. In telling the tragic tale of the fall of the old-wings and gigantic air dragons, it’s easy to forget the flip side of that story. Despite all the species and orders that died then, lots of others lived on, and they speak volumes about the insects’ resilience and adaptability. Most of the survivors were species with novel adaptations, such as advanced neopterous wing flexing and complex metamorphosis. The new-winged insects with wing-folding mechanisms could fly faster, hide better, and outcompete the old-winged insects. New feeding innovations like the invention of refined fluid feeding mouthparts allowed insects to successfully colonize different plants in upland areas. The evolution of larval stages enabled them to invade plant tissues and more successfully avoid large predators. Insects proved themselves resilient in the face of continental collisions, global climate change, massive volcanic eruptions, and substantial geochemical
changes in the oceans. In fact, despite the challenges they encountered while colonizing the land during the Silurian years, insects proved in the Permian that the conquest of land was a winning strategy. As cockroaches demonstrated to the trilobites, if there was ever a good time not to be in the oceans, it was during the end of the period.

Maybe it’s perilous to divide the history of life into separate ages, but in this case perhaps we can indeed pick one singular moment when the Paleozoic era came to an end. I’d choose the particular day when the final trilobite died. What other creature better symbolizes the entire era than the trilobite? Their reign in the oceans lasted for more than 300 million years, but some 252 million years ago, on a cloudy morning perhaps, the last one stopped feeding in a shallow tidal pool. Her body floated to the surface, and the retreating tide washed it ashore along with other trilobite carcasses. Where were the black birds of death? Who witnessed that event? There were no shore birds on that lonely beach, but there was a scurry of small feet, as first one cockroach, then another, found the castaway body and consumed it. Maybe a lone beetle, preening its antennae on a log nearby, briefly flew down to inspect the scene and partake in the feast. Then it turned, unfolded its wings, and buzzed clumsily into the forest. The Paleozoic years had ended, to quote the poet T. S. Eliot, “not with a bang but a whimper,” and the insects declared themselves the victors. But soon there would be a new rustling in the Mesozoic forests; with slashing claws and gnashing teeth, the first dinosaurs would appear. How would the insects get along with their new roommates?

PLATE 1. The disruptive coloration of the malachite butterfly,
Siproeta stelenes
, provides excellent camouflage in the dappled understory of the tropical dry forest at Chamela Biological Station in Jalisco, Mexico. Examples of the largest butterfly family, Nymphalidae, they fly rapidly when disturbed.

PLATE 2. Can you see it? Motionless on a leaf, this Ecuadorian katydid nymph (order Orthoptera, family Tettigoniidae) displays remarkably cryptic green coloration. (Photo by Angela Ochsner.)

PLATE 3. Stalking the mossy Ecuadorian cloud forest at night, this well-camouflaged praying mantis nymph (order Mantodea) uses crypsis to its advantage while hunting insect prey. (Photo by Andy Kulikowski.)

PLATE 4. Hiding in plain sight, this very cryptic katydid demonstrates another method of camouflage: by resembling tree bark it is well adapted to surviving the prolonged dry season at the Chamela Biological Station in Jalisco, Mexico.

PLATE 5. Seemingly confident in its ability to rapidly jump away from danger, this Ecuadorian short-horned grasshopper (order Orthoptera, family Acrididae) is sitting pretty at the Yanayacu Biological Station in Ecuador. (Photo by Angela Ochsner.)

PLATE 6. Voracious predators of other insects, the assassin bugs (order Hemiptera, family Reduviiidae) impale their prey with their piercing mouthparts and suck out the fluids. (Photo by Angela Ochsner.)

PLATE 7. Literally stuck in one place, the sap-feeding spittlebug nymphs (order Homoptera, family Cercopidae) cover themselves with bubble-laced honeydew. This Ecuadorian species may acquire defensive chemicals while feeding, since it also displays bright aposematic warning coloration. (Photo by Angela Ochsner.)

PLATE 8. These
Altinote neleus
butterflies (family Nymphalidae) commonly gather roadside at mud puddles on sunny afternoons at the Yanayacu Biological Station. Perhaps overly confident in their toxic defenses and aposematic coloration, they can be picked up by hand and will exude orange toxic fluids from their bright abdomens. Although they are well evolved against predation, they have not adapted to the modern world and are often run over by passing vehicles. (Photo by Angela Ochsner.)

PLATE 9. Seldom seen by daylight, the enormous tusk-jawwed males of
Corydalus hageni
(order Megaloptera, family Corydalidae) sometimes fly to lights at the Yanayacu Biological Station.