Speckled wood (butterfly) facts for kids

Quick facts for kids Speckled wood
Male P. a. tircis
Male underside
Scientific classification

The speckled wood (Pararge aegeria) is a beautiful butterfly. You can find it in and around forests in many parts of Europe and Asia. This butterfly has several types, called subspecies. These include Pararge aegeria aegeria, Pararge aegeria tircis, Pararge aegeria oblita, and Pararge aegeria insula.

The color of these butterflies changes depending on the subspecies. Their wings can be brown or orange. They have spots that might be pale yellow, white, cream, or a reddish-orange color. Speckled wood butterflies eat different kinds of grass. Male butterflies have two main ways to find a partner. They either defend a small area or fly around searching. The way they choose depends on where they live and the conditions around them. Females usually mate only once. They pick a male that they think will help them have healthy offspring. This choice is also affected by the environment.

What's in a Name? (Taxonomy)

The speckled wood butterfly belongs to a group called Pararge. This group has three species. These are Pararge aegeria, Pararge xiphia, and Pararge xiphioides. Pararge xiphia lives on an island called Madeira in the Atlantic Ocean. Pararge xiphioides lives on the Canary Islands.

Scientists have studied these butterflies closely. They found that the butterflies from Africa and Madeira are related. They are different from the ones in Europe. This suggests that butterflies came to Madeira from Africa. It also means the African butterflies have been separate from European ones for a long time.

As we mentioned, the Pararge aegeria species has four subspecies. These are Pararge aegeria aegeria, Pararge aegeria tircis, Pararge aegeria oblita, and Pararge aegeria insula. These different types exist because the butterfly's features change gradually across its home range. This is like a gradient. For example, a butterfly might look a bit different if it lives in the north compared to one in the south. These changes create the different subspecies in various geographical areas.

How to Spot a Speckled Wood Butterfly (Description)

Both male and female speckled wood butterflies have an average wingspan of about 5.1 cm (2 in). That's about the length of a credit card! Males are usually a little smaller than females. Males also have special grayish-brown scent scales on their front wings. Females do not have these. Females often have brighter and clearer markings than males.

Different Looks for Different Places

The P. a. tircis subspecies is brown. It has pale yellow or cream spots. Its upper wings have darker eyespots. The P. a. aegeria subspecies has more orange on its wings. Its hindwing eyespots are reddish-brown, not black or dark gray. These two forms slowly blend into each other where their ranges meet.

The P. a. oblita subspecies is a darker brown, almost black. Its spots are white instead of cream. The underside of its hindwings has a light purple band. It also has a row of clear white spots. The spots of the P. a. insula subspecies are a reddish-orange color. The underside of its front wings has light orange patches. The underside of its hindwing has a band with a purple tint. Even with these differences, it's usually easy to tell the subspecies apart.

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  Female speckled wood butterfly

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  Underside of a female

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  Close-up of a female's head

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  Hairs on the wings of a female

The butterfly's body shape changes along its geographic range. Butterflies in the north are generally bigger. They have larger bodies and wings. These measurements get smaller as you go south. However, the length of their front wings increases as you go north. This is because in cooler northern areas, butterflies need bigger front wings. These larger wings help them warm up their bodies. Northern butterflies are also darker than southern ones. This color difference also changes gradually across their range.

Where They Live (Habitat and Range)

The speckled wood butterfly lives in many different places. You can find it in forests, grassy areas, meadows, and clearings. It also lives in cities. Look for it near hedges, in wooded parks, and sometimes even in gardens. Within its home range, this butterfly usually likes damp areas. It is found in woodland areas across much of Europe and Asia.

The P. a. tircis subspecies lives in northern and central Europe, parts of Asia, Russia, and central Asia. The P. a. aegeria subspecies is found in southwestern Europe and North Africa. There are two more subspecies in the British Isles. The Scottish speckled wood (P. a. oblita) lives only in Scotland and its nearby islands. The Isles of Scilly speckled wood (P. a. insula) is found only on the Isles of Scilly. The P. a. tircis and P. a. aegeria types slowly blend into each other where their territories meet.

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  Male P. aegeria, underside view. Colchester, Essex, England.

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  Male P. a. aegeria in Portugal

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  Underside of a male P. a. aegeria from Portugal

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  Female P. a. aegeria from Cyprus

The Butterfly's Life Cycle

An egg with a tiny butterfly embryo inside

Larvae. A newly hatched larva and a fully grown larva are shown next to a human finger for size.

A pupa, also called a chrysalis

Speckled wood butterflies lay their eggs on various types of grass. The caterpillar (larva) is green and has a short, forked tail. The chrysalis (pupa) can be green or dark brown. This species can survive winter in two different stages. Some overwinter as pupae, and others as half-grown larvae. This means that several groups of adult butterflies can emerge each year.

What Caterpillars Eat

The caterpillars eat many kinds of grass. Some examples include Brachypodium sylvaticum, Dactylis glomerata, and Holcus lanatus. However, their favorite food is often couch grass (Elytrigia repens). Adult butterflies drink nectar from flowers.

Growing Up: From Larva to Adult

How speckled wood butterflies grow depends on how many other larvae are around. It also depends on if they are male or female. If there are many larvae in one place, fewer of them survive. They also take longer to develop and become smaller adults. Female butterflies are more affected by this. They need the food they ate as larvae to lay eggs later. So, if there were too many larvae, females might lay fewer eggs as adults.

Males can make up for being smaller by eating more as adults. They can also change how they look for partners. So, high larval numbers don't affect males as much. Growing very fast can also be risky for larvae. If food becomes scarce, those that grew fast might lose weight quickly. They might not survive even if food becomes available again.

Finding a Partner (Mating Behavior)

Female speckled wood butterflies usually mate only once in their lives. Male butterflies, however, often mate with several females. To find females, males use two main strategies. They either defend a sunny spot or fly around searching.

When defending a territory, a male waits in a sunny patch in the forest. He waits for females to fly by. The other strategy is patrolling. Patrolling males fly through the forest actively looking for females. A female then chooses whether to mate with a patrolling male or a territorial male. Mating with a territorial male can mean she has chosen a strong male. This is because being able to defend a territory shows a male's good qualities. So, by choosing a territorial male, the female is being more selective.

The female's choice often depends on how much effort it takes to find a partner. When a female actively searches for a male, she uses up valuable time and energy. This is especially true if she doesn't live very long. If it costs a lot to search, females might be less picky. For example, if a female's life is short, it costs her more to search for the perfect mate. She might mate within a day of becoming an adult. She would likely mate with a patrolling male, as they are easier to find. If a female lives longer, it costs less to search. She is more likely to look for a territorial male. Since these search costs change with the environment, mating strategies vary among different groups of butterflies.

Males using different strategies can sometimes be told apart by the spots on their hindwings. Males with three spots are more likely to be patrolling. Those with four spots are more likely to be defending a territory. How often you see these two types depends on the location and time of year. For example, there are more territorial males where there are many sunny spots. Also, the environment affects how these wing spots develop. So, the strategy a male uses depends a lot on the conditions around him.

Defending Their Space (Territorial Behavior)

Territorial defense involves a male flying or sitting in a sunny spot. This spot is usually where sunlight shines through the forest trees. Speckled wood butterflies sleep high in the trees. They start their territorial activities once the sun hits the forest floor. Males often stay in the same sunspot all day. They follow it as it moves across the ground. They usually perch on plants close to the ground. If a female flies into the territory, the male resident flies after her. They then land on the ground and mate. If another type of butterfly flies through the sunspot, the male usually ignores it.

However, if another male speckled wood butterfly enters the sunspot, the resident male flies towards him. They almost bump into each other. Then, the two butterflies fly upwards. The winner flies back down to the sunspot. The defeated male flies away from the area. How they fly during this encounter depends on the plants around them. In an open area, they fly straight up. In a dense area with many plants, they spiral upwards instead.

Most of these conflicts are short. The male who lives there usually wins. The intruder likely gives up because a serious fight could be risky. There are also many other good sunspots available. But if both males think they are the "resident" male, the fight can become more serious. If a male tries to get his territory back after leaving to mate, a longer and tougher fight happens. In these serious fights, it's hard to predict who will win.

How much territorial behavior you see depends on the environment. At the start of the mating season, fights over sunspots are long. The length of these fights quickly gets shorter over about two weeks. This pattern matches the season's progress. As the temperature rises and there are more males, sunspots become less important. Sunspots are more attractive when temperatures are low. They provide warmth that helps butterflies be more active. As more males appear, it becomes harder to hold onto a territory. So, males defend territories less, and more males start patrolling instead.

Wing Shapes and Success

Butterflies can have wings that are not perfectly symmetrical. This means one wing might be slightly different from the other. This can happen in a few ways. Sometimes it's small, random differences. Other times, one wing is consistently larger.

Both male and female speckled wood butterflies can have asymmetrical wings. However, only males show a specific type where one wing is often larger. This might be due to their genes. Females generally show more asymmetry than males. Among male speckled wood butterflies, darker males show more of this specific asymmetry. They also grow slower than the paler, territorial males. Interestingly, males who are most successful in territorial fights are only slightly asymmetrical. They are not perfectly symmetrical or very asymmetrical. This suggests that choosing a mate might be linked to wing symmetry.

Making New Butterflies (Reproduction and Offspring)

A female's ability to lay eggs depends on her body weight. Females who don't get enough sugar during their egg-laying period lay fewer eggs. So, heavier females usually lay more eggs. The number of eggs laid might also be linked to how long she spends looking for a good place to lay them. When a female lays many eggs, the eggs are usually smaller. However, studies found that egg size didn't affect how well eggs or larvae survived. It also didn't affect how long larvae took to develop or the weight of the pupae. One idea is that females balance laying many eggs with finding the best spot. In a perfect environment, a female would lay more eggs. This helps her have more offspring and pass on her genes.

How Males Help with Eggs

When butterflies mate, the male gives the female a special package. This package contains what's needed for fertilization. It also has a lot of proteins and fats. The female uses these nutrients to produce her eggs. In some butterfly species, females mate with many males. This leads to competition among males. In those cases, males try to give a large package. This helps them fertilize more eggs and might stop the female from mating again.

However, most female speckled wood butterflies mate only once. This means there's less competition among males. So, the male's package is much smaller compared to other species. The size of this package increases as the male's body weight increases. If a male mates a second time, his package is much smaller. This means mating with a male who hasn't mated before results in more offspring. So, there's a small disadvantage for females who mate with a male who has already mated.

Look-Alike Butterflies

• Pararge xiphia (Fabricius, 1775) the Madeiran speckled wood butterfly
• Pararge xiphioides Staudinger, 1871 the Canary speckled wood