Many planthoppers are adorned with irregular spikes and crests, while others employ ridiculously intricate kinds of mimicry, such as weevil mimics (Eurybrachidae: Ancyra) that walks backwards, jumping spider mimics (Derbidae: Rhotana) that rotate in place, or ant mimics (Caliscelidae: Formiscurra) that probably run about. Among those that strive to lie undetected there are the thorny helmets of Membracids, well known for a dual role in crypsis and defense, but as the forms they take on become increasingly bizarre, it calls into question what function they could possibly serve. Another group of planthoppers that likewise exhibits extravagant head structures are the lantern bugs (Fulgoridae). In Costa Rica, over 30 species of fulgorids have been described, each with morphologies so distinct that it is difficult to misidentify them as adults. The most famous species is one that easily dwarfs them all— the peanut-headed bug (Fulgora laternaria).
Peanut-headed bugs are so large that they have well outgrown their jumping capabilities, relying on the typical side-to-side shuffles before a sudden fluttery flight upwards to the canopy. Although the head is light and hollow, it still shifts the bug’s center of mass forward, which requires many wingbeats to achieve a rather inefficient flight. Common names are not always on point, but it’s easy to see why the peanut-headed bug is so aptly named— if there were peanuts growing in the rainforest soil I might have even started digging for a chance to find their look-alike. Despite seeing numerous of their bristled foamy egg cases over the years, I had never found an adult, but that finally changed last summer. This individual appeared to have recently eclosed, as evidenced by a dusting of white wax on its head, and no matter how I turned it, the bug was persistent in its preference to face upwards. After staring for countless hours, I still could not make any hypothesis about what its head may be mimicking, if anything at all! It wasn’t until many months later that I found a paper likening them to arboreal lizards due to a similar resting posture, “eye” and head profile, and scaled pattern on what would be the lizard’s lower jaw. I’m usually not a fan of far-reaching mimicry stories, such as wing tips of some saturniid moths resembling a snake head, but the idea of lizard mimicry is virtually absent for any animal group, and I thought it would be a fun possibility to mention.
The dragon-headed bug (Phrictus quinquepartitus), though substantially smaller than Fulgora, is equally perplexing in its intentions. My shot-in-the-dark hypothesis is that the protuberance resembles a spiny orb-weaver (Micrathena spp.), a relatively unfavorable prey item — just having fun here — so feel free to write in the comments if you have any suggestions! Phrictus and many other fulgorids, including Enchophora (pictured below), have bright colorful or spotted hindwings. When fleeing from a predator they will expose their colorful hindwings in flight, followed by a stationary posture with the wings closed which hinders a predators recognition ability. It’s also well documented that they use the hindwings in a deimatic display to startle and deter a predatory threat, but across all my encounters thus far I’ve failed to elicit such a behavior. Dragon-headed bugs are a seldom sight unless you know their host tree where they feed on sap. At La Selva Biological Station, you can find dragon-headed bugs on almost every large guayabo tree (Terminalia oblonga).
Fulgorids are understudied relative to other homopterans, but rising to the limelight are their symbioses with nectarivorous affiliates. All lantern flies secrete honeydew from the abdomen, the sweetness originating from the plant phloem they ingest. Such copious amounts of honeydew are released that the bugs must flick the secretions away from their feeding sites to prevent fungal growth and unwanted attraction from birds or monkeys. This behavior has lent itself nicely to associations with opportune arthropods that lie in wait to feed upon these ephemeral sweet resources— termed trophobiosis. Across 145 nocturnal observations in four Fulgorid species, symbionts included moths, cockroaches, ants, and surprisingly, land snails. For the dragon-headed bug in particular, large Camponotus ants and the snail (Euglandina auriantiaca) were the most common. Continuing with the theme of fulgorid-lizard associations, in Madagascar, geckos (Phelsuma, Lygodactylus, Homopholis) have been found to feed on planthopper secretions in a purported vibratory dialogue, and observations also extend to Malaysian geckos (Hemidactylus, Cyrtodactylus, Gehyra) with fulgorids (Dichoptera, Prolepta, Pyrops). In Costa Rica, I’m willing to bet the yellow-headed gecko (Gonatodes albogularis) is a likely candidate. These interactions are probably much more common than we think!