In the insect world, there is a type of clown wearing colourful clothes with green 🟢, yellow 🟡 and red colours 🔴. They are called 𝘗𝘺𝘳𝘰𝘱𝘴 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢 (Linnaeus, 1758), known as Longan Lanternflies. We often find these colourful and intricate bugs feeding on lychee and longan trees in Hong Kong🌳. That’s why they are called the longan lanternflies or “lychee lanternflies” 🤣. But have you ever wondered what is so special about the colourful pattern and “horn🦏” of the Longan Lanternfly? Let’s find out more!
𝘗𝘺𝘳𝘰𝘱𝘴 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢 belong to the Fulgoridae family, which includes nearly 800 species globally. While some Fulgoridae species can reach 9 cm in length, the size of 𝘗. 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢 is more modest, but still averaging 4-5 cm long, which is relatively large for an insect. This species is widespread in Asia, extending from Fujian to East India and south to Indonesia. They are famous for their green and yellow pattern and red “horn”. Speaking of their red “horn”🔴, it looks like the red nose of clowns. There’s a myth saying that the horn-like structure is luminous at night, but it’s not. Others may mistake this structure for their nose for breathing. In fact, it is just a hollow structure that is nearly as long as the body, but some have suggested that this long process is quite flexible and is used by the insect-like a springboard to eject itself from the plant it is resting on. However, the Fulgoridae family has only undergone a few in-depth studies in the past. That’s why there are uncertainties about their physical characteristics, especially their head morphology.
Moreover, their colourful pattern is an essential feature for their survival. Their bright colours allow them to carry out aposematic colouration. The bright colouration is recognized as poisonous and dangerous in the natural world, so this indicates unpalatability to predators, which may increase longan lanternflies' survival. At the same time, they show a different colour when they spread their wings open. Bright yellow hind wings 🟡with black dots of 𝘗. 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢 appear when they fly while showing their green 🟢forewings when they land. This kind of colour difference mechanism confuses their predators thinking they are not the same bugs and thus do not attack them. Imagine you are a bird trying to catch the green longan lanternfly on the tree. When you are approaching it closer and closer, it suddenly flies away. You quickly try to track the route that it flies. However, what you see is an insect with yellow wings flying. That’s not what you are looking for! Never mind, let’s find another prey instead!
Another special feature of 𝘗. 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢 is its eating habits! Just like clowns, they can perform magic tricks to produce honeydew🔮✨. In plants, the phloem is the vascular tissue allowing the transport and distribution of organic nutrients. The sap circulating within the phloem of plants is rich in sugar which attr acts longan lanternflies. They have a long and sharp proboscis, which is a type of mouthpart that is basically a tube, to help the insect suck up nectar. This structure can reach the phloem to get juicy sap by piercing the tree trunk. But if the sap contains a high level of sugars, on the other hand, it has a low quantity of nutrients that insects need for their development. As a result, 𝘗. 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢 needs to suck an important amount of sap to meet its requirements in nutrients. However, just like for us, too much sugar is a problem🍬. The solution is thus to excrete this excess of sap from their body in a liquid known as honeydew! This honeydew will then be used as free food by other animals, such as geckos and ants, providing an ecological service to their neighbourhood. These organisms can then be observed at the back of the lanternflies, waiting for the honeydew to drop! In Thailand, there was an observation on the mutualism between lanternflies and geckos. It was observed that there were 20-30 lanternflies and 4-5 geckos waiting at the back of them on the same tree. In some other species of Hemiptera (bugs) facing the same problem, the honeydew is used for bartering protection from ants against potential predators, but this does not seem to be the case in 𝘗. 𝘤𝘢𝘯𝘥𝘦𝘭𝘢𝘳𝘪𝘢.
Do have a closer look if they are dripping sap when you meet them🍯!
Text: Lydia Chang