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When you look at the butterfly above, what do you immediately see? Yes, the clue was in the title of this article, but we definitely can make out the number 88 on its wing.  Found in Middle and South America, these butterflies are, unsurprisingly called mariposa ochenta y ocho (eighty-eight butterfly) in Spanish. Image Credit

 

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Perhaps more of a revelation is that, depending on where you are, you might not be looking at the same species. Just as we have not one “8” but two, so there are two distinct species with variations of the name the eighty-eight butterfly (there are 12 altogether, it would have been more fun had there been eight).   Of course, they certainly share one big thing in common, but evolution shaped the wing pattern for survival, not for numeracy (and more about that later).

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The two most common species are the Diaethria clymena (known as Cramer's eighty-eight) and Diaethria anna (Anna's eighty-eight). They are distinguished by the patterns on their hindwings: D. clymena has a thicker, bolder “88” pattern with more pronounced red accents, while D. anna shows a slimmer, more delicate “88” with subtler red markings. 

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Their dorsal (top) wing colours also differ slightly, with D. clymena often showing broader blue or greenish bands, and D. anna having narrower, darker bands. These differences make it possible to identify each species in the field.  You can see the dorsal differences above – but perhaps that can be left to the lepidopterists.  Most people who see one of these butterflies simply calls it an “88”, whether it’s Anna’s, Cramer’s or another of the 12.

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Like many species, the 88 is choosy when it comes to food (at least in its caterpillar stage).  It feeds only on trema, a small to medium deciduous tree (up to 12 m) with spreading branches, smooth grey bark with visible lenticels, and hairy twigs.  Trema grows in rainforest and cloud-forest habitats between sea-level and 2000m, and so that’s where you will find the 88.

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Once the caterpillar has transformed into a butterfly, the diet changes. The 88s like nothing more than rotting fruit.  They rarely stay in one spot for longer than a few seconds but do stick around the same area and return frequently to the same patch of ground – as long as there is rotting fruit on the ground.  This is, perhaps, when they are at their most susceptible to predators and where their markings come in handy.

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Both sexes are attracted to rotting fruit. The males are strongly attracted to urine-soaked sand, and also imbibe dissolved minerals from damp soil, road surfaces and rock faces. They are very active butterflies, easily disturbed, and rarely settle for more than a few seconds at a time in one spot, but they will return repeatedly to the same patch of ground.  

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It is rare to see more than three 88s together, but they are known to gather in larger groups at places to which they are particularly attracted.  They seem to have adapted well to our presence, and like being around the ash at the site of campfires, and seem to like the smell of laundry too.  If you want to attract some, urinate on some bare ground – and if they are in the vicinity, the 88s will come.  They also like being by water.

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Sometimes, they may not end up at their intended destination.

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As the day cools, the male butterflies will bask in the sun, but by nightfall all the 88s settle below leaves which will protect them from any overnight rainfall.  They are, regardless, quite hardy and numerous – and a relatively common in their habitat.

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So why do they have the 88 markings?  Some butterflies use toxins from host plants (like monarchs with milkweed) to deter predators.  This is not the case with the 88 – the trema does not contain toxins which can be passed down to the adult butterfly.  Although we can’t be 100% sure, the bold 88 pattern may mimic warning or eyespots.  This can trick birds or lizards into thinking the butterfly is dangerous or just make them hesitate. This is called Batesian mimicry and makes an animal looking dangerous without actually being poisonous.  The “88” is on the underside of the wings because butterflies rest with wings closed and so that’s the surface predators see most.

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However, we don’t see a warning, we see a number. Humans are extremely good at spotting numbers, faces and familiar symbols. Our brains are wired to find meaning in random shapes - a phenomenon known as pareidolia. It’s why two simple circular wing markings can instantly register in our minds as 88.

On a lighter note, a social media user once asked: “Where are butterflies 1 through 87?”  The witty reply that they received was “Iterations 1-87 of the universe were not stable and the simulations were terminated. What you see is indeed a version indicator of our universe. So far v 88 has been stable but might be showing signs of deterioration.”   

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Yet sometimes other iterations do appear; nature provides us with the occasional 89.  Perhaps that’s a sign of change in the near future?