What does it mean to see 100 million butterflies flying together? You will know when you go to Jinping County

Butterfly is one of the insects that everyone is familiar with. It is deeply loved by people because of its beautiful appearance. The dancing butterflies have also become the business cards of some places, such as the world-famous migration of the monarch butterfly Danaus plexippus (Linnaeus, 1758).

Every summer, countless monarch butterflies roam in the woods of North America. When they fly, they are like flower rain falling with the wind, and when they stop, they are like cascading waterfalls, which is extremely spectacular.

Do we need to go to North America to see this wonder? In fact, you don't have to bother. You can also see this amazing and beautiful landscape in Jinping County, Yunnan Province, my country.

Part 1

Jinping County and its Butterfly Valley

Jinping County is located in Honghe Hani and Yi Autonomous Prefecture in the southeast of Yunnan Province. It is located in the southeast branch of Ailao Mountain. It has a large altitude difference, with the highest altitude being 3,074 meters and the lowest altitude being 105 meters. The biogeographic region belongs to the Red River system and is located in the tropical monsoon climate zone. Therefore, the climate is rainy and warm, with distinct dry and wet seasons.

Jinping County's complex climate and geographical pattern have created a multi-layered ecological landscape, providing conditions and foundation for the high butterfly species diversity here.

According to statistics, there are currently 271 species of butterflies belonging to five families, 137 genera, and 56 other species recorded in Jinping County, accounting for about 13.4% of the total number of butterfly species in my country. Moreover, with the deepening of investigation and research, many new and newly recorded butterfly species have been discovered.

According to media reports, in mid-June this year, Jinping County will see an estimated 100 million butterfly outbreaks, mainly Stichophthalma howqua iapetus Brooks, 1949 and S. suffusa tonkiniana Fruhstorfer, 1901.

People and butterflies dance together during the Butterfly Valley eruption in Jinping County

Image source: Gao Fei

Both the North Vietnamese subspecies of Stichophthalma and the North Vietnamese subspecies of Stichophthalma in western China belong to the genus Stichophthalma (Stichophthalma Felder & Felder, 1862) of the subfamily Morphinae of the family Nymphalidae, among which the North Vietnamese subspecies of Stichophthalma is more numerous.

Both the North Vietnamese subspecies of the Arrow-ring butterfly and the North Vietnamese subspecies of the Western Arrow-ring butterfly are large butterflies, with forewings 51-55 mm long, large heads, thin and short antennae, thick chests, and thin and short abdomens; the forewings are broadly triangular with rounded apex angles and straight trailing edges; the hindwings are wide and spread with serrated outer edges; the front base color is brownish yellow, and all the markings are black; the apex angles of the forewings are black, and the outer edges of the forewings and hindwings have a row of arrowhead patterns with the tips pointing inward; the back is brownish yellow, with two nearly parallel black fine lines in the middle area, a row of red circular eye spots on the sub-outer edge, and two wavy black fine lines on the outer edge.

The North Vietnamese subspecies of the Antelope butterfly and the North Vietnamese subspecies of the West Chinese Antelope butterfly are very similar in appearance, but the North Vietnamese subspecies of the Antelope butterfly has no obvious color difference on the front of the forewings, and there are no scattered black scales between the arrowhead patterns on the outer edge of the hind wings. The two can only be distinguished by these two characteristics.

Comparison of the North Vietnamese subspecies of the butterfly and the North Vietnamese subspecies of the butterfly. The top is the North Vietnamese subspecies of the butterfly, and the bottom is the North Vietnamese subspecies of the butterfly. The left side is the front and the right side is the back.

Image source: provided by the author

Specimens of the North Vietnamese subspecies of the Chinese butterfly were collected as early as 1956. Due to its similar appearance, the North Vietnamese subspecies of the Chinese butterfly was mistakenly identified as the North Vietnamese subspecies of the Chinese butterfly for a long time. It was not until 2021 that it was published as a new record species of Chinese butterfly.

The growth process of the Arrow Ring Butterfly is also very distinctive. From the time they are insects to the time they pupate and become butterflies, they often live in bamboo forests.

The life cycle of a butterfly

Image source: veer

The larvae of the butterfly feed on bamboo leaves. The eggs are hemispherical and often laid on bamboo leaves. The larvae also have the habit of gathering on the leaves. The larvae have a large black head, a slender light green body with many dark green longitudinal stripes, and fine white hairs on the body surface. The area around the pores on the sides of the body is yellow. The dark stripes become lighter in mature larvae.

The pupa is a hanging pupa, that is, it is fixed only by the tail, with no silk thread surrounding the middle. It is nearly ellipsoidal, emerald green, with a fine yellow line in the middle and a red dot in the middle of the fine line. The whole resembles an unripe berry.

Butterfly chrysalis under leaves

Image source: provided by the author

When the adult emerges, the head first emerges from the top of the pupa, and after it is completely out, it hangs on the pupa or other fixed objects with its legs. The arrow butterfly that has just emerged from the pupa cannot fly because its wings are wet and wrinkled. At this time, it needs to inject body fluids into the wing veins to open the wings, and wait until the wings are dried and hardened before it can fly.

Adult butterfly often moves in bamboo forests, flying slowly up and down between trees, especially in the evening. They like to gather near water to drink water or eat rotten fruit.

The southern part of Yunnan Province is the only clearly defined distribution area of ​​the North Vietnamese subspecies of the Angustifolia and the North Vietnamese subspecies of the West Chinese Angustifolia in China.

Part 2

Causes of the outbreak of the butterfly in Jinping County

The outbreak of the Arrow Ring butterfly in Jinping County is the result of the combined effect of many factors, and we have not yet fully revealed all the reasons for this phenomenon. However, with in-depth research, more and more causes are gradually surfacing.

First of all, the Angustifolia is an insect with one generation per year. Its adult phase is from May to July every year. Almost all the Angustifolia butterflies will break out of their pupae and transform into adults during this period. This is an important reason for the outbreak of the Angustifolia butterflies in Jinping County.

Secondly, a suitable habitat is also an important factor. Since the Butterfly likes to live in warm and humid valleys, its number is largest in Ma'andi Township, which has a lower altitude. The Butterfly outbreak here is also the most spectacular.

In addition, as mentioned above, the larvae of the butterfly feed on bamboo leaves, and there are a large number of bamboos growing in Ma'andi Township, which provides a food basis for the huge number of butterfly larvae.

In addition, factors such as temperature, precipitation and humidity will also affect the distribution and survival of the arrow-ringed butterfly, further providing conditions for the occurrence of butterfly outbreaks.

Jinping County Butterfly Explosion

Image source: Zhao Yi

In fact, there are many examples of butterfly outbreaks in China, such as Aporia genestieri (Oberthür, 1902) in Lijiang City, Yunnan Province, A. crataegi (Linnaeus, 1758) in Northeast China, Euploea sp. in Guangdong Province, etc., all of which have periodic large-scale outbreaks. Therefore, the outbreak of the Arrow-shaped butterfly in Jinping County is not an isolated case.

However, this phenomenon is the largest and most densely populated outbreak of butterfly species known in China. Therefore, the outbreak of butterfly species in Jinping County is one of the most important objects in domestic butterfly research, and is of great value to our exploration of the formation mechanism of butterfly outbreaks.

The dancing butterflies are spectacular and charming, and are a great gift from nature to us humans. I believe that with the deepening of research, we will eventually be able to solve the mysteries behind the explosion of the arrow-ringed butterfly in Jinping County. This magical phenomenon will also become an important material for studying the diversity of butterfly species in my country and Ailao Mountain.

References:

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Produced by: Science Popularization China

Author: Zhang Huihong (Yunnan University)

Producer: China Science Expo

Editor: Wang Tingting

The article only represents the author's views and does not represent the position of China Science Expo

This article was first published in China Science Expo (kepubolan)

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