Specimen Showcase | Sweet Poop on Trees🍯

If you are an avid reader of our posts, you may have realized that at the HKBM, we like to bring your attention to organisms that may go unnoticed to most👍🏻. Today’s group is just like that despite having fantastic and bizarre shapes and colors. The treehoppers are insects that became masters of mimicry and are armed with beautiful and elaborate miniature ‘helmets’ and ‘horns’, resembling seeds, spines, prickles, keels, caterpillar poops💩, and even ants🐜! Most treehopper species have a small body length under 12 mm despite their exquisite appearances. In addition to their solitary personality, when one individual stays still in its camouflage outfit, it could be hard to spot on a plant stem or branch🤔.

𝘛𝘳𝘪𝘤𝘦𝘯𝘵𝘳𝘶𝘴 𝘺𝘢𝘨𝘰𝘪 (Kato, 1940) belongs to the most diverse treehopper family, the Membracidae, which contains over 3200 described species worldwide. It is on average 7 mm long but the impressive pair of thick horns present on either side of its head makes it look bigger. In addition, these horns are fused to extend backwards and form a single long thorn, which covers more than two thirds of its pronotum, the shield-like plate covering its thorax (the middle-part of the body supporting the legs). Interestingly, these fierce looking horns are not used as daggers to capture prey, but as defensive mechanisms to protect the treehopper against the curiosity of potential predators . Treehoppers are peaceful insects that behave more like cattle than wolves😌. Indeed, these sap-sucking insects will spend most of their lifetime on their favourite host plants.

Treehoppers fed on plant sap and cell tissues by inserting their needle-like mouthparts into plant stems🧃. Species of the plant genus 𝘗𝘳𝘶𝘯𝘶𝘴 (including the dark-spotted cherry native in Hong Kong) offer the preferred food for𝘛. 𝘺𝘢𝘨𝘰𝘪. Once the insect is “attached” to a desired spot through its long mouthparts, it would start sucking day and night😋. The mouthparts of a treehopper is composed of two sharp tubes, allowing them to inject saliva into the plant and suck plant sap at the same time💉. The saliva is injected to prevent the plant from healing the wound generated by the insect, and therefore, offers all the time needed by the insect to ingest large quantities of sap.

Treehoppers are loyal tenants, especially females, who tend to stay on the same host species throughout their lives💘. A study on the genus 𝘌𝘯𝘤𝘩𝘦𝘯𝘰𝘱𝘢 sp., another member of the Membracidae family, has provided more evidence on the above hypothesis. It has been observed that females stick to the plant 𝘨𝘦𝘯𝘶𝘴 on which they developed. On average, females only mate once while males have a chance to mate up to four times. Hence, males are the ones dispersing from their original hosts searching for virgins, while mated females would stay and reproduce where they were born👩‍❤️‍💋‍👨.

This sedentary lifestyle could make them particularly vulnerable to predators😦. But thanks to their defensive outfits, protective camouflage, with some treehopper species really hard to differentiate from the plant itself, treehoppers are able to overcome the appetite of potential predators. On some occasions, however, treehoppers will entertain the taste for sweet of particular predators. Indeed, plant sap is rich in sugars but poor in nitrogen, an essential compound in the development of insects. As a result, large quantities of sap (and thus sugar) are ingested to fulfill the nitrogen requirements, leading our treehoppers to become “treepoopers”😳. These large amounts of sweet excreta are very attractive to some of the fiercer predators in the neighborhood: ants🍯! Those will not only feed on the honeydew produced, but also protect the treehoppers against potential predators, or fungi that could grow on this pile of … Together, some treehopper and ant species will form mutualistic interactions, where each of them will find benefits at cooperating with the other🤝.

How interesting is the insect world! Next time, try to find these tiny thorn bugs on plants, maybe some ant bodyguards may betray their presence🧐. And if you want to learn about the beauty of insects and other organisms, make a booking at the HKBM now😝!

Text: Millian Hui

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