Common field grasshopper facts for kids
Quick facts for kids Chorthippus brunneus |
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The Chorthippus brunneus, also known as the common field grasshopper, is a type of grasshopper. It belongs to a group called Gomphocerinae. This grasshopper is very common across western Europe, Asia, and northern Africa. The IUCN (a group that checks on animal populations) says it is a species of Least Concern, meaning it is not in danger of disappearing.
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What They Look Like
Common field grasshoppers are usually brown. But they can also be many other colors like black, green, purple, or even white! Their wings can have different patterns too. Some have spots, some have stripes, and some are plain.
Green and purple grasshoppers often have plain wings. Black ones usually have spotted wings. Brown grasshoppers can have any wing pattern.
Where They Live and What They Eat
C. brunneus grasshoppers live in dry places. You can find them in Europe, north Africa, and parts of Asia. They like heathland areas more than farms. This is because heathlands have taller grass (100 to 200 mm high) and fine-leaved grass types. They especially like Agrostis and Festuca grasses.
When animals like cows or sheep graze, they eat the grass short. This means fewer grasshoppers live there. In places where grass is not eaten short, C. brunneus grow faster, get bigger, and have more babies.
These grasshoppers are herbivores, meaning they only eat plants. They are also polyphagous, which means they eat many different kinds of plants, but mostly grasses.
How They Reproduce
Common field grasshoppers have one generation per year. This means they complete their life cycle once a year.
Mating Calls
Male grasshoppers sing to attract females. They do this by rubbing their legs against their wings, a process called stridulation. If a female is interested, she will sing a similar song back. The male will then sing again. If a female sings back, it makes it more likely they will mate.
Having Babies
Female grasshoppers in areas with fewer grasshoppers have more babies than those in crowded areas. They also live longer in less crowded places.
Bigger females tend to lay more eggs. Also, the number of eggs a female lays depends on the length of her back leg.
Hybrid Grasshoppers
In northern Spain, C. brunneus sometimes mate with another type of grasshopper called C. jacobsi. They form a hybrid zone, which means they create mixed-species babies. Scientists think these two types of grasshoppers became different species during the Pleistocene ice age.
Both grasshoppers have the same number of chromosomes. But C. brunneus has an extra piece of rDNA on its X chromosome that C. jacobsi does not have. This extra piece does not seem to do anything.
C. brunneus and C. jacobsi also have different songs. They also have different numbers of tiny pegs on their back legs, which they use to make sounds.
C. brunneus are more common in August, while C. jacobsi are more common in June and July. C. brunneus only live in valleys, but C. jacobsi live in both valleys and mountains. This helps keep the two species separate.
Female grasshoppers (both C. brunneus, C. jacobsi, and their hybrids) prefer the songs of pure C. brunneus or C. jacobsi males over hybrid male songs.
How They Grow
C. brunneus grow through stages, changing their skin as they get bigger. This is called hemimetabolous development. Females lay their eggs in the soil over about 10 weeks. The eggs hatch in April. Young grasshoppers, called nymphs, usually go through four stages before they become adults. Adults can live until late autumn.
Eggs and Young Grasshoppers
C. brunneus lay eggs in dry, sandy places. In labs, they lay the most eggs between 28-35 °C.
Smaller eggs might seem weaker, but eggs from warmer southern areas are smaller and survive better. This is because warmer winters help them.
Egg size changes with the mother's age. Older mothers lay bigger eggs. Eggs laid at the end of the breeding season are smaller because the mother's health is not as good.
Grasshopper eggs need to absorb water to survive. They can lose a lot of water but cannot survive if they dry out completely.
Bigger eggs usually mean bigger young grasshoppers and bigger adults. Eggs laid in late August to early September are the heaviest. They hatch later but grow into heavier young grasshoppers. Young grasshoppers that hatch earlier are smaller at first but grow to be larger adults.
Warmer weather and less food can make later-hatching grasshoppers grow faster but stay smaller. Grasshoppers from colder places tend to be the heaviest when they hatch. If there are too many grasshoppers in one place, they develop slower and become smaller adults.
Winter Sleep (Diapause)
C. brunneus eggs spend the winter in a special resting state called diapause. They can stay in this state for up to a year at 5 °C and still hatch. In a lab, scientists can make eggs hatch by keeping them warm (25 °C) for two weeks, then cold (4 °C) for several weeks.
Extra Growth Stage
Some female C. brunneus in East Anglia, Britain, have an extra growth stage (called instar IIa) between their second and third nymph stages. This extra stage helps them grow larger. Females of C. brunneus are usually 3 to 4 times bigger than males. Longer summers in East Anglia might help them hatch earlier and grow faster, allowing for this extra stage and a larger size.
Growth Speed
How fast a grasshopper grows is not affected by how humid it is, but it is affected by heat. Grasshoppers that get heat from a warm lamp grow six to seven weeks faster than those that do not. Nymphs also grow quicker when there are fewer grasshoppers around.
Males and females weigh the same until their third growth stage. After that, females become heavier than males. Females take longer to grow because their growth stages last longer. However, males grow more steadily and live longer than females.
In England, grasshoppers from northern areas grow faster and have shorter growth periods than those from southern areas.
Their Songs
C. brunneus make sounds by rubbing their stridulatory pegs against their wing covers, called elytra. Their normal calling song has 5-12 notes, each lasting about 0.25 to 0.50 seconds. After singing, they rest for about 3 seconds before repeating the song.
Males sing a "rival song" when they meet other males. They sing during the pauses in the other male's song. These rival song notes are much faster than normal song notes.
"Courtship songs" are sung by males trying to mate after their normal song did not work. These songs are softer but at higher frequencies. If the male is not successful, he will sing some short, loud notes before trying the courtship song again. If a female is interested, she will sing back, and they will sing together in an "attraction song."
Male C. brunneus can sing different types of songs and even vary the same song. Males with "average" song characteristics are best at attracting mates. Their songs are also affected by the environment around them.
Pollution and Grasshoppers
C. brunneus are used as bioindicators for heavy metal pollution. This means they can show how much pollution is in an area. They are often found in places with heavy metal pollution, like Szopienice and Olkusz in Poland.
These grasshoppers can have high levels of heavy metals in their bodies. Being exposed to heavy metals changes how their body enzymes work. Grasshoppers from polluted places have higher levels of certain chemicals (like glutathione) and lower activity of some enzymes.
When grasshoppers are exposed to zinc during their winter sleep, they have lower levels of glutathione. Another chemical called Dimethoate makes the effects of heavy metals even worse. It reduces the activity of important enzymes by almost 50%.
Scientists think that grasshoppers in polluted areas have to use more energy to deal with the harmful effects of heavy metals. This means they have less energy for growing and developing.
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