"If we want to be accurate, crickets and grasshoppers don't actually sing. Their chirping doesn't come from their 'mouths.' Grasshoppers produce their chirping by rubbing their toothed hind legs against their forewings, while crickets create sound by rubbing one forewing against the other. Together with katydids and other similar insects, they belong to the order Orthoptera," explained Teder.

According to the scientist, mostly male grasshoppers and crickets chirp. Similar to many birds, the primary function of this sound is to attract females. It's much easier for a female to locate a chirping male than a silent one. The quality of the chirp also matters; for instance, it has been found that in some species, females prefer males with louder chirps.

"Only adult, sexually mature males chirp among crickets and grasshoppers. Nymphs do not chirp. Since these insects overwinter as eggs and develop into adults over time, this explains why we start hearing more chirping after midsummer. Female grasshoppers also chirp to some extent, but their chirping is more subdued compared to that of males," added Teder.

Chirping can serve purposes beyond attracting females. In some cricket species, males use chirping to signal to other males that a territory is already occupied. Just as in attracting females, males that chirp louder often have more success in claiming territory.

However, Teder noted that there is a downside to enthusiastic chirping. Predators of grasshoppers and crickets can also hear the chirping, which can lead them to a potential meal.

Chirping differs from one species of grasshopper to another

According to Tiit Teder, the strength, rhythm, frequency and duration of chirping vary greatly among Orthoptera species. As a general rule, grasshoppers primarily chirp during the daytime, while crickets chirp either both day and night or only at night.

Some species chirp continuously for minutes, while others produce chirps that last less than a second. There are species that chirp very faintly, and some do not chirp at all. "For example, the chirps produced by the sickle-bearing bush cricket (Phaneroptera falcata) are at the threshold of audible sound and are easier to detect with a bat detector," explained the entomologist.

In total, 25 species of grasshoppers and 13 species of crickets have been identified in Estonia. Some, such as the migratory locust (Locusta migratoria), known primarily as a pest from nature documentaries, and species like the oak bush-cricket (Meconema thalassinum) and Bryodemella tuberculata, have only been observed occasionally in Estonia.

"There is no reason to believe that they will establish more permanent populations here. The most common grasshoppers in Estonia are the bow-winged grasshopper (Chorthippus biguttulus), Chorthippus dorsatus, common field grasshopper (Chorthippus brunneus) and Chorthippus apricarius. Among crickets, the most widespread are the bog bush cricket (Metrioptera brachyptera), the Roesel's bush-cricket (Roeseliana roeselii), Tettigonia cantans and the wart-biter (Decticus verrucivorus)," Teder added. However, not all species are found throughout Estonia. For instance, the dark bush-cricket (Pholidoptera griseoaptera) and the great green bush-cricket (Tettigonia viridissima) are primarily found in western Estonia.

Could climate warming bring us new grasshopper and cricket species?

According to Tiit Teder, there is a considerable possibility of seeing new species in Estonia due to climate change. For instance, the sickle-bearing bush-cricket, first observed in Estonia in 2014, has now established itself and is sometimes quite numerous. "There is no need to fear the migratory locust, however. It is not present in large enough numbers anywhere in Europe to cause economic damage," added the scientist.

Besides chirping, crickets and grasshoppers have a small but important role in the local ecosystem, according to Teder. "As primarily herbivorous insects, they consume a certain amount of plant biomass. While their impact on plant biomass in our ecosystems is quite small, especially compared to the damage migratory locusts can cause in the tropics, grasshoppers and crickets are an essential food source for many birds, as well as mammals and reptiles," Teder said.

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