Last week continued to be hot and sunny. There was not a drop of rain. The trails through the forest are now becoming heavily cracked. The lawns around the lodge are definitely more brown than green. The forest however remains vibrant, there is no sign of drought stress. The huge volume of water that fell as rain last November has ensured that the creek is still running quite well, more so than would be expected for this time of year. The dry season is typically when a lot of leaf fall occurs. That is the case at the moment. The trails are cleared and a few days later there is a layer dry, brittle brown leaf covering the path once more. Some of the trees that have been in bloom over recent weeks are coming to the end of the flowering period.
Brushing Toxic Hair
Although I spend my days monitoring butterfly populations and see plenty of the adults flying around, it is only very occasionally that I see the larvae or caterpillars. It may well be that because I am not actively searching for them that I am not seeing them. There are over 7,000 named species of butterfly in the Neotropics and that number is dwarfed by the number of moth species. Many butterflies and even more moths have unknown life histories. Quite often we don’t know what the larval form looks like or what host plant they feed on.
Caterpillars are the feeding and growing period of the butterfly or moth life cycle. Feed and grow they do and at an amazing rate. Caterpillars are quite often restricted to feeding on a single species of plant, sometimes on a few species within one genus or sometimes several species in the same family. Each species does not have a large variety of choices. After hatching from the egg, the caterpillar can increase in size by over a hundred times before it pupates.
Being a large, constantly and rapidly growing creature, the caterpillar has to remain unseen by predators or if seen, then has to have a secondary range of defenses such as irritating spines or hairs or to feed on plants poisonous to other creatures, store the toxins within its own tissues and warn off potential predators with bright warning, (aposomatic), coloration.
Over recent weeks I have stumbled across several caterpillars as I was out walking around the forests of the Osa Peninsula. I was not looking for them, they just happened to catch my eye. Any caterpillar sporting a battery of spines or hairs is one that you should avoid handling. The spines and hairs may exude toxin secretions that can cause intense irritation.
The caterpillar of the Saddleback Moth, (Acharia hyperoche), usually hides on the underside of the palm leaves on which it is feeding. It has green coloration that helps it blend in with its background. The saddle marking may help to break up its outline. If the ruse does not work and it is spotted by a keen-eyed predator, then it has a second line of defense. The body anterior, posterior, laterally and dorsally has fleshy protuberances that carry batteries of sharp urticating spines. The slightest brush against this living, toxic slug-like creature will result in a red itchy rash and a certain degree of pain. Many other species of moth in the same family, Limacodidae, are protected in the same fashion.
Another group of species which belong to the Silkmoth family, Saturniidae, more particularly of the subfamily, Hemileucinae and the genus Automeris also have caterpillars which protect themselves in a similar fashion. The body is green and quite literally covered in urticating bristles. The adult Automeris moths are very distinctive too. The dorsal surface of the forewings are colored and patterned to resemble dead leaves. Should anything disturb these particular leaves though they are in for a shock. The forewings swing forward which reveals two large eye-spots on the dorsal surface of the hindwings. As far as the predator is concerned it could well be looking at a much larger predator staring back at it from the ground.
Sometimes it may prove prudent to let a potential predator know that you are likely to cause them harm when touched. Some of the Dagger Moths, (Acronicta spp), caterpillars are covered in long lemon yellow hairs with contrasting black tufts. If touched these hairs can break and become embedded in the skin. The longer black hairs are attached to a gland than secretes a toxin that will leave a nasty little rash on human skin.
As well as the finding of caterpillars is difficult, then locating the chrysalis’s is equally, if not more, challenging. Admittedly I don’t go looking for them and so if I do discover one then it is entirely by chance. The one species that I find more than others is the Narrow-banded Owl-butterfly, (Opsiphanes tamarindi). That may be due to the fact that the larvae feed on Heliconia, Maranta and Bananas of which there are many plants around the bar and restaurant areas of Bosque del Cabo. A chrysalis has little by way to defend itself and so crypsis might be the best option. Green coloration is a good way of camouflaging yourself against a background of green vegetation. This one I noticed hanging from the underside of a leaf beside the bar.
Grumpy Big Head
There are six species of Anolis lizards living on the Osa Peninsula. On the grounds of Bosque del Cabo Rainforest lodge I have encountered five of those species and the remaining one as an ,isolated population several miles away.
When I was out walking the Titi Trail this week I saw a the Big-headed Anole, (Anolis capito), lying languidly on the root of a large fig tree. As I slowly approached with the camera in hand, it opened one of its eyes and looked at me with a doleful expression as if to say don’t even think of bothering me. But I did take some photographs and each time the flash went off the lizard moved, almost imperceptibly, further around the root in a direction away from me.
The Big-headed Anole is one of the larger anolis lizards in this area. It attains a length of 9 inches including the tail. It’s body color is a mottling of greens, greys and browns. It can be found on the trunks of trees where it normally perches head down waiting for food items, arthropods or small lizards, to pass by.
Two of the more commonly seen anolis lizards are the Slender Anole, (Anolis limifrons), and the Golfo Dulce Anole, (Anolis osae). Both of these species can be commonly found around human habitation. The Slender Anole as the name suggests is a small slim species, mottled brown in color and with a white underbelly. The Golfo Dulce Anolis is slightly more robust and uniform brown in color, (at least the males), with a distinctive white stripe along the body behind the shoulder. Both of these species live close to the ground, again facing head down but usually at the end of large leaves.
The last two species in this immediate area is the Green Canopy Anole, (Anolis biporcatus), and the Lichen Anole, (Anolis pentaprion). They both tend to live higher up in the canopy. I see the Canopy Anole more often at night where I find it lying asleep on the tops of leaves. It’s bright lime green coloration stands out quite nicely in the beam of a flashlight. The Lichen Anole I have found at the top of the canopy. It is grey in color with pale spots. Both of these two anoles I only find very occasionally whereas the other three can be found without much effort.
Philip Davison is a Biologist, Writer and Photographer Based in Costa Rica