That’s not an owl... right? (Owl Butterflies)

This week we are looking at Owl Butterflies, their behaviors, and why they got the name! 

 

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This weeks artists: HM Surf, mønberg, no one's perfect, and sleepermane 

 

Transcript: 

 

Welcome to episode 32 of Insects for Fun! I’m your host Mitchel Logan and this week we are taking a look at one of my favorite butterflies and the largest butterfly in the Americas, the Owl Butterfly.. 

 

Owl butterflies are 20 some odd species within the genus Caligo, and are found from Mexico down into South America, flying in both the rainforests and secondary forests. Secondary forest means that the forest has regrown after a cutting or clearing either from a natural or manmade process. 

 

The butterfly as stated in the intro for this episode is indeed the largest butterfly within the Americas and its got a wingspan ranging between 6.5-20cm depending on the species. Blue morphos can also get up to this size and share a similar coloring, often making the two confusing to distinguish between for a novis butterfly watcher. And yes butterfly watching is in fact a hobby much like bird watching and on the topic of birds, Owl butterflies get their name because of the very large conspicuous eye spot seen on both their outer hindwings as well as the patterning and coloration. The under/outward-facing wings really do resemble an owl, especially a horned owl. Pictures will of course be on the instagram page along with their caterpillars.

 

The inner/upper facing side of the wings vary heavily by the species with some being more black and monocolored than others, but they do often have blue which does not help at all for people who already have difficulty differentiating them from blue morphos, but! If you listen to this episode and check out the instagram page then you too can be confident the next time you encounter one of these butterflies! My favorite is Caligo atreus which sports bright blue and cream orange on the inner wings, and its outer wings look like they went through a warm vintage filter. 

 

The caterpillars for these butterflies are pretty monstrous as well, competing in size with the Hickory horned devil which we mentioned last episode, these caterpillars can reach a length of 15cm but their appearance is very different. So different in fact that the caterpillars for these look like hairy slugs. Yes, that is an oxymoron but there seriously is no better description. The tail end of this caterpillar is slimmer than the mid section and forks into two tails that look like eye stocks on a slug and the head is also narrow and flattens into the body. Something un-sluglike would be the tufts of fur that poke out of their back. Some species have longer tufts than others which look like a row of spikes going down where a spine would be. I’ve seen them in person while at a butterfly house in Montreal Canada and they really are huge and unlike any other caterpillar I’ve seen. 

 

Earlier I mentioned that the genus for this group of butterflies is called Caligo and there is a good reason for this. Caligo in Latin means darkness or the dimness of light and as it turns out, these butterflies are actually crepuscular which is just a fancy word for being active at Dawn and Dusk. Next time someone asks why you look so tired during the day just hit them with the I’m crepuscular and I’m sure they won't bring it up again. But honestly its really cool to see them flying around in the evening or dawn because the last thing you expect to find mid-flight is a giant butterfly.  During the day these butterflies like to perch under large foliage and rest. It’s a smart move because predators would have no trouble finding them in flight during the day. 

The butterflies feed in the evening hours on a variety of things from rotting fruit and animal dung to flowers from heliconia, fan palms in the family Cyclanthacea (also referred to as Panama hat palms), and Bananas, but Banana trees are not native to the neotropics. The primary diet is definitely rotting fruit though which is why you find so many of them clustered around bananas, mangos and other common fruits at butterfly gardens. It’s actually quite common to see them in exhibits that offer an indoor butterfly room along with Blue Morpho butterflies probably because they are some of the largest butterflies in the world and easy to raise.

 

The caterpillars feed on the same plants the adults fly to making them a pest on banana and plantain farms.

 

 So much so that it was apparently proposed to use parasitic wasps on farms in certain countries to lower their populations. Now I tried to find records of this but I wasn’t able to and to be honest, I feel like releasing parasitic wasps in a neotropical country would require a huge amount of testing to make sure the wasp wouldn’t affect native populations of other insects. Unless of course, it is a native wasp! But moving along to the topic of predators, owl butterflies actually have a semi erratic flight pattern as seen with blue morpho butterflies to help protect them from being targeted by birds, reptiles, and other predators. These butterflies don’t fly for long durations at a time and end up frequently pausing on trees and other hard surfaces which confuses animals that are trying to lock on. 

I’ve actually experienced this firsthand in the forests of Belize while walking down a path when an owl butterfly flew into view. I had a net ready but I could not keep track of its zig-zag flight and random pauses in the brush. Suffice to say it got away and I ended up in a pile of mud, but that’s just how it goes sometimes. 

 

Owl butterflies also partake in a behavior known as lekking which is when male butterflies stake out a territory and then compete with each other for the attention of a female.  

 

These butterflies usually line up along a forest edge or along a road and sit waiting for a female to fly by. 

 

 The males actually scent these territories using pheromones and will even fight off other males who fly into their lekking space. If a female flies into the territory of a male he will pursue her for a short while to see if she’s interested  And if she’s not, that’s just the way it goes and he will fly back to his perch. What’s odd is that the areas males choose to lek aren’t very strategic in terms of resources. Often times these locations don’t have anything in particular that would attract an owl butterfly. They usually aren’t even in an area the butterflies would normally inhabit either. It’s like these butterflies specifically choose areas where they stand out and can really show off what they have. The funny part is that males will often be relatively close to each other but not close enough to overlap their territories. It really feels like a show hall where females fly slowly down the line to choose which male they want.  

 

This usually happens at dusk or dawn with many observers claiming that the phenomenon only lasts until the sun makes it over or under the horizon depending on the time of day.