By William Bower |
Cicadas are from the order Homoptera, which includes plant lice and leaf hoppers. Worldwide there are over 2,500 different species of cicadas that reproduce in cycles, with certain generations emerging after periods of 2, 5, 13 and 17 years. There are three broods of 13-year cicadas and 12 broods of 17-year cicadas in existence, which occur only in the eastern half of the United States. Over 150 species of cicadas occur in the United States and Canada. An article appearing in the New York Times stated that insects outnumber humans, 200 million to one. Scientists have calculated that the world holds 300 pounds of insects for every pound of humans.
Locusts are grasshoppers in the order Orthoptera, along with crickets and katydids. When grasshoppers join a swarm they are known as locust; therefore, the locust is not a species but a name for a swarm of grasshoppers. The only difference between a locust and a non-locust grasshopper is the swarming behavior. Locust do not always swarm; however, after a period of wet weather, leading to over crowding and vegetation gone in one area, they gather together in a swarm to find food somewhere else. They can travel up to 100 miles a day. At this time, the grasshoppers bump into each other, activating hormones that cause changing of color; breeding more frequently and laying more eggs. Our word cicada comes from the Latin word cicala, meaning tree cricket; while the word locust comes from the Latin word locusta, which describes the voracious grasshopper (locust) that travels in swarms and destroys vegetation. The word is related to the Greek word lekan, meaning to jump.
Our annual cicada is often referred to as the dog-day cicada, which appears during the long-hot summer days. These annual dog-day cicadas are larger than the periodical cicadas and have two to five-year life cycles; however, the broods overlap, with some appearing every summer.
Only the male cicadas sing, with the singing done to attract mates. Each song is specific to their species. The singing is produced by two noisemakers known as tymbals that are located on each side of the abdomen. Cicadas produce their sound (a click) by contracting these tymbals, and another click as the muscles are relaxing. The male abdomen, which is largely hollow, acts as an amplifier and creates a loud call. While periodical cicadas sing in a chorus, the annual (dog-day) cicadas sing independently of other cicadas in the area. If disturbed, dog-day cicadas will squawk as they take flight to escape danger.
Grasshoppers are more slender and longer in shape than cicadas. Their hind legs are built to jump, and their wings are not as long as their bodies. Although grasshoppers are mostly green or brown, they also have a variety of colors. Grasshoppers are not nearly as loud as cicadas, and their songs are produced by rubbing either their wings together or their wings against their legs.
Although the cicadas are commonly eaten by birds and other animals, their biggest enemy is a fungal disease. When an annual cicada is singing and danger is approaching, its call will be softened to distract the attention of the listener to neighboring louder singers. The periodical cicadas have an unusual defense to protect themselves from predation, with the number of cicadas emerging at once far exceeding the amount that predators can eat. When all of the predators are sated the cicadas can breed in peace.
A mated cicada female will lay her eggs in a slit in a twig that she made with her ovipositor. After the eggs hatch, the nymphs drop to the ground, where they will bury themselves and feed on the roots of deciduous trees.
The dog-day cicadas take two to five years to mature to adults, at which time they emerge from the ground to begin the life cycle again.
Grasshoppers simply lay their eggs in the soil, with the nymphs hatching the following spring.
By the middle of September, we no longer hear the cicadas calling, and we won’t hear the calling of the dog-day cicadas again until the heat of next summer.