Watching butterflies fly around my garden the other day I wondered how they and other insects find a mate when they need to reproduce. I was surprised at the information I found.
Insects use senses to find a mate. Many rely on pheromones to attract a mate, while others use their eyesight or sound to attract a mate. Some insects then go through an elaborate courtship display.
Most species of insects live solitary lives, living over great areas in different habitats and shared with other similar species. For insects to find another of the same species to mate they first have to find each other and also recognize each other. Insects attract each other using their senses of sight, sound, or smell.
Insects mainly use the sense of scent to attract a mate. The strongest scents are usually given off by the female allowing the male to find them. Pheromones, as the scents are called are chemically unique to each species so the male knows that it is pursuing the correct female. Once mating has ended then the female stops giving off pheromones.
Pheromones of moths have shown that pheromones can travel for long distances. The studies showed that males could find a flying female up to two miles away.
The study also showed the number of pheromones that would attract a male. In tests, the male could find a female after pheromones were released at just one-tenth of a thousand of a millionth of a gram.
The cecropia moth, North Americas largest native moth has feathered antennae. These increase the area available to detect tiny molecules of pheromone.
Although many insects use their sense of smell to find a mate, many insects, especially insects that come out during the day, use their eyes to recognize and find a suitable partner.
This is especially the case in insects that are brightly colored such as butterflies. The bright colors of the butterfly have evolved to allow them to attract mates easily. The most beautiful colors are displayed on the surface of the upper wing.
Butterflies can change their appearance, effectively giving them two different looks. Butterflies can go from having a bark-like camouflage to brightly colored just by changing the position of their wings.
Females do most of the flying during the mating season with males establishing a territory, sitting on a branch and waiting for the female to fly past. The male will then fly close to her and try to persuade the female to land with him. Any other males are chased away by the first male. Although color plays a huge part in courtship, pheromones confirm to the male that he has found a female of the same species.
Female dragonflies will not mate with a male if they have already mated. Males are prone to fighting to prove dominance to the female and injuries can be severe. When the female enters the males territory the male flies up to her to mate.
Grasshoppers and crickets use sound to communicate and use sound to find a mate. Grasshoppers have tiny pegs on the inner side of each hind leg. These small pegs are then stroked against veins on their forewings to make a sound. Different species of grasshopper have a different number of pegs which makes each species sound individual.
Males sing to the females using this method which is called stridulation. The song attracts females which will reply to the male. Although females have weaker pegs and therefore a weaker sound, the hearing of the grasshopper is excellent. They hear using organs which are located on each side of the base of the abdomen.
Stridulation is done different between grasshoppers and crickets. Crickets use their wings to make sound. A row of pegs along the overlapped forewings makes noise when rubbed against a ridge when the wings are moved quickly. The placement of the hearing organs is also different. Crickets have theirs on the fourth segment of their forelegs. Only male crickets make noise using stridulation.
Cicadas are another vocal group of insects that use song to attract a mate. Only the males make noise which attracts the females. The process they use to make sound is different with a stretched membrane at the bottom of the abdomen vibrating. Cicadas can be extremely loud compared to other insects.
As with plenty of other types of animals once an insect has found their mate using sound, sight and smell, they may have to undertake a courtship display to win the female over.
Many species of butterflies go through courtship displays. The female Arctic grayling, once they have met using pheromones and sight will sit on the ground facing the male. The male will then open and close his wings several times before clasping the antennae of the female in them.
The antennae transfers scented scales called androconia from the males wings to her olfactory receptors. This stimulates the female to mate. The androconia is different to the original pheromone released by the female to attract the male.
How Do Nocturnal Insects Find Mates?
Nocturnal insects cannot rely on sight and color to find a mate like daytime insects unless they are bioluminescent. Glow-worms is the common name for various groups of insect larvae. Although still at an early stage, the larva does reach maturity. They lay in the grass at night and their abdomen shines brightly with a luminous glow.
Although the female is at a larvae stage the male is a mature beetle. The beetles flies until around and when they see the luminous greenish-yellow abdomen of the larvae they will fly down to mate.
Fireflies produce light in an organ on the underside. Males will flash lights while flying. When mating they use a specific sequence of flashing lights. Males will flash every six seconds before waiting for a flash from the females. If a female is present and wants to mate they will twist their abdomen towards the male, flashing back after one to two seconds. This will continue until the male reaches the female.