14 DAY TRIAL // Mammals and birds may be the most complex organisms, but insects have won the evolution race. There are about 900,000 described species, and scientists evaluate their real number from 2 to 10 million species. Calculating the total number of insects on the globe, researchers found it overpasses by 200 billion times the number of humans.
Insects are masters of the flight. Mosquitoes can fly with the abdomen upward. Some can fly in the rain without getting soaked, by slipping between the rain droplets. Some tropical wasps and bees can fly with 72 km (45 mi) per hour, while locusts and dragonflies can fly with 45-60 km (29-37 mi) per hour. The monarch butterfly of North America makes migrations 3,200 (2,000 mi) long. Some fly can beat their wings more than one thousand times per second, faster than a hummingbird. And even the bee has a wing beat of 230 per second. Dragonflies can fly backwards (amongst vertebrates, only hummingbirds can do this).
The insects' reproductive power is amazing: in warm conditions, in less than one month, a locust turns into adult and each female deposes hundreds of eggs during a season.
In a little cloud of locusts, covering 100 square kilometers (40 square miles), there are about 70,000 tons of insects, thus several tens of billions of locusts, each weighing 2 grams.
In fact, in some environments, in just one square kilometer live more insects than humans on the whole planet. Ants make in ecosystems 15-25 % of the total animal biomass.
Just one ant colony cleanses of other insects a surface of 2-3 forest hectares. The army ants (Eciton), found in tropical America, have colonies of 100,000 to 2,000,000 individuals, that will kill and eat everything in their paths and in other species, the colonies can count for 20 million individuals. Even in a bee hive, there are 80,000-100,000 individuals.
To store one honey kilogram (2.5 pounds), the bees of a hive must visit roughly 7 million flowers and make 240,000 km (150,000 miles), which means 10,000 flight hours.
Locusts and grasshopers can jump over 10 times their length, and fleas 200 times their body length (it's like humans jumping 360 m (1,200 ft))!
Insects' feet present on the top adhesive pads, covered by special hairs, that enable them walk on ceilings, vertical walls and even viscous surfaces. Scientists are attempting to imitate this.
The termite colonies, made of millions of individuals, build mounds that can be 7.5 m (25 feet) tall over the soil but underground, they can be 75 m (225 feet) deep and extend hundreds of meters away. It's like us building an edifice as big as the Himalayan Mountains. These constructions have sophisticated installations of conditioned air and underground fungi gardens. And all these builders are blind!
Not only termites, but ants too cultivate fungi. The leaf cutting ants (Atta) chop tree's leaves and gather the leaf remains from the forest floor, carrying all into their underground nests. All is ground into a soft mix with which they feed their underground fungi gardens. The ants maintain the gardens at the optimum values for temperature and humidity for getting the best results. The new leaf layers are "seeded" with older material and to increase crop production, the ants even "weed out" the layers. The production is adapted the the colony's food necessity, saving this way time and energy. The gardening implies sustained work.
The insect metamorphosis is an amazing phenomenon per se. From a maggot, a fly comes. A caterpillar turns into a butterfly: it's like turning a train into a plane. The dragonfly larva lives in the water feeding on little fish and tadpoles; the adult fly freely hunting insects. Would you imagine a human living the first 20 years swimming in the sea, and after that flying like a bird?
Insects have 5 eyes: three small ocelli and two big compound eyes. Flies have sharp vision sense and reflexes ten times more rapid than ours. Many insects, like butterflies and bees, see in ultraviolet light. The eye of many insects works like a compass: bees and wasps can detect polarized light, allowing them to establish sun's position on the sky even when hidden by clouds. This way they will always know how to turn back home.
Insects rely heavily on pheromones for communication. A male butterfly's sophisticated antennae will pick up just one molecule of pheromone, tracking a female found 11 km (7 mi) away.
Crickets, grasshopers and cicadas prefer "serenades" for attracting a mate, their ears being placed on the thorax. Those made by male cicadas are stronger than the noise emitted by a pneumatic drill.
Insects are cold-blooded and just like snakes and lizards, they take sunbaths in the morning. Some beetles are attracted by the water lilies flowers, which have a temperature 20o C higher than that of the environment. Butterflies have an incorporated heating system: when requiring heat, they open their wings which act like solar panels and tilt them towards the sun direction.
Insects can have many special properties. Some butterflies extract salt and humidity from cattle's tears and dung. Other insects, possessing a powerful antifreeze, enabling them to inhabit snowy peaks eating on beetles that died of cold.
Even many people consider insects annoying, we need them. About 30 % of our food depends on the pollination made by bees, most of them wild. Insects maintain the soil clean by recycling dead plant and animal matter. The soil gets fertilized and nutrients help plants grow. In Australia, Europeans introduced cattle. Local insects did not process cattle dung, and the dung boosts the populations of bush flies, an annoyance for both people and cattle. The problem was solved by bringing dung beetles from Europe and Africa.
Some insects attack crops and carry diseases, but only 1 % of the insect species are considered pests, and many produce increased damages due to the way people manage the environment. Malaria mosquitoes rarely bother the inhabitants of the rain forests, but they make mayhem in the cities filled of pools at the edge of the forests.
Crop alternation and preserving insects' predators can control their numbers. Ladybirds destroy aphids, while dragonfly larvae eat the mosquito's larvae.