Broadcast 30 November 2005, the next programme deals with flying insects. It begins in Central Europe, where the Körös River plays host to millions of giant mayflies as they rise from their larval skins to mate. — the climax of their lives. Mayflies and dragonflies were among the first to take to the air about 320 million years ago, and fossils reveal that some were similar in size to a seagull. Damselflies are also looked at in detail. One species, the rare cascade damsel, inhabits waterfalls, while another, the helicopter damsel, lives away from water (unlike all the others in its group) and is also the biggest. Several types of butterfly are shown, but all have common habits, and Attenborough describes their physiology. Together with moths, they possess the largest wings, and this surface area gives ample opportunity to display for partners or warn off predators. In cold weather, bumblebees must warm themselves to prepare for flight: they 'disable' their wings, enabling them to exercise their muscles without taking off. The vestigial rear wings of flies and crane flies are used for navigation, and arguably the most accomplished insect aviator is the hoverfly, which makes continuous adjustments while in the air to remain stationary. Beetles that are capable of flight have to keep their wings below covers, and a specimen of the largest, the titan beetle, is shown. Attenborough attempts to entice a male cicada, only to have it land on his ear (causing laughter from the camera team).
Production of the series took around two years, during which time filming took place around the world, from the Amazonian rainforest to Costa Rica, Australia, Malaysia, Hungary, Switzerland and many more locations, including the United Kingdom. To follow and understand the various species looked at throughout the series, the production team consulted with some of the foremost experts on invertebrate life. In certain instances, their help proved invaluable, particularly when coming across particularly dangerous species or societies. In other instances, the specialists helped to provide some of their most recent discoveries, enabling the makers to showcase in rich detail the complex processes through which invertebrates may interact with their environment, as well as the regular processes of all animals in the wild, such as their mating rituals and hunt for food. Many of the creatures' interactions were not only filmed for the first time, but were also recorded with such extraordinary magnification that scientists who studied them were able to answer specific questions that observance with the naked eye had hitherto rendered impossible.
Filming of mayflies was made possible by their appearance on the last day.
As always, time and money constraints played a huge part. The filming schedules had to be arranged to fit in with expected dates of major events that were planned to be included, such as the emergence of the North American cicadas or the mass emergence of mayfly in Hungary. As is usual in the preparation of a nature documentary, not everything went to plan, due to the unpredictable nature of the subject matter. Although filming took place over several years, time constraints still meant that some scenes almost weren't filmed, and a few never materialised at all. For instance, the simultaneous mass emergence of the mayfly in Hungary did not occur until the deadline day for its filming, as David Attenborough had to be in Switzerland the very next day to film the mating of wood ants. Using expert advice, the team had come to film at the time of the annual emergence, but the problem of the unusually wet spring had delayed the event. Luckily, on the very last day conditions were perfect, and the mayfly emerged — apparently in one of the more impressive manifestations of recent times. Because of these kinds of occurrences being largely dependent on environmental factors such as temperature or moisture, it was nearly impossible to tell exactly when they would happen. Instead the producers had to rely on expert estimates, but even these could be completely unpredictable. So although the mayfly appearance was captured, others were missed, such as the advent of a type of moth in Arizona (despite the camera crew camping out in the area twice, two weeks at a time). Sometimes subjects were so small that it would have been impossible to film them in the wild. Instead, the construction of a complete habitat in a studio allowed easy pursuit of their actions, allowing the camera to capture them throughout their day. This technique was used on the wolf spider, for example, which provided some 200 hours of film — notably including its courting ritual. Despite the arm span of the grown spider being no more than 1cm, even the newborn arachnids are shown in tight close-up as they climb on to their mother's back.
Filming also involved entering rough environments. To film the giant centipede, a team had to endure a dark cave whose floor was covered with guano, beetles and cockroaches.