Butterflies and other insects

Butterflies and other insects

Those who have visited the ecology section will have seen that Perú contains a significant fraction of the world's biodiversity. Butterflies have a major following, and they are amongst the best-studied of the insect groups. It turns out that twenty percent of the world's species of butterfly are to be found in Perú. The best estimate is that over 4000 species live in the Andes rim and in the jungles of Perú. One can only guess at the extent to which other, lesser studied insect groups are represented. Our thanks to Jeff Pippen of Duke University for his help with this brief introduction. See here for a web site with many photographs of moths and butterflies.

Both butterflies and moths belong to the insect Order, Lepidoptera, and there are many more species of moths in Peru (and in the world) than butterflies. However, we know of over 3500 species of Perúvian butterfly. Regions that are separated by only a few hundred kilometres may share only 60% of their endemic species, and many are extremely local. Of the 1,300 species in the Manu park, for example, probably 30-40% are endemic. Butterflies in the Northern part of Amazonas are largely distinct. While Peru has many beautiful moths,perhaps some of the most often noticed are the Urania Moths. They are vivid green, black, and white and look (and act) like swallowtail butterflies. They are frequently seen along dirt roads in the jungle regions.

As with other types of insects, Peru is home to an impressive diversity of ant species, from tiny ants about a millimeter long to the giant "Dinosaur Ants" that are 3cm long! While many ants are harmless to people, some like the Bullet Ant can pack a very powerful sting, so one should look carefully before sitting down on a log in the jungle. Some of the more delightfully entertaining ants include the leaf-cutter ants. These ants cut out pieces of leaves with their mouths and then carry them back to the nest to make a type of garden. The ants grow fungi on the chunks of leaves and then the ants eat the fungi. One can see processions of them on lianas, looking like minature demonstrators waving their placards.

Why Perú is so rich in endemic species remains open to speculation. Theoreticians believe that the jungles of Perú, much as with those of the Asian "Wallace line" islands, were havens of forest in a world of savannahs and frost during the last ice age, and that species radiated out from these when the climate warmed. It is plainly obvious, however, that the edge of the Andes marks a location of many transitions. The Andes dip into flat forest land which extends largely unchanged for 4000 km to the Atlantic ocean. This area is called the ceja de selva, the eyebrow of the jungle.

Butterflies gather on the road near Oxapampa in the ceja de selva

The intersection is exceptionally rich in niches. There is limestone and Andesite, basalt and schist; and the forest varies with the geology. The interwoven steep hillsides and forest, open ground and dry patches creates a myriad of niches, of diverse plants and variable predators. Climate can vary very greatly from one valley to the next, or in a few hundred metres of ascent.

The richest zone for seeing butterflies is undoubtedly the alta selva and ceja de selva. The recognised centres are around Moyobamba in the North, Tingo María in the central area, Chanchamayo further South and the South, where the Manu park and Tambopata offer extraordinary numbers of species. Whether this richness is reflected in the real species abundance, or just the relative ease of entry into these areas as compared to the deep jungle is a matter of speculation. The electric blue flashes of the Morpho butterflies of the deep jungle are everywhere evident, as are a host of other species on the jungle pathways. The blue iridescence is due to an interference pattern rather than a dye. That is, the layers of keratin that make up the individual wing scales are so spaced that they reflect only light of a certain wavelength - in this case, blue. It is interesting to hold up the wing of a dead example and to see that it looks brown to transmitted light. The wings of the larger Morpho species can cover 90 square centimetres, and extend to 18 cm. from the insect's body.

San Martin is one of the least explored areas in the ceja de selva, as it was (and is) the centre of coca cultivation, from which is derived cocaine. Its jungles contain unexplored ruins of ancient cultures. The higher reaches are sear, dry altiplano, whilst the lower parts, near Tarapoto, Juanjui and Tingo María, are semi-seasonal rain forest. The Cordillera Azul, however, rises from these to 2000m and receives near constant cloud and rain. It its foot, the Huallaga river runs into lowland forest: wet, steamy and insect-rich. Each of these areas has its characteristic species, and many of these have varieties which differ with the ecosystem in which they find themselves. Heliconiinae and Ithomiinae butterflies often form large mimicry rings which vary with region. Those found in the high-altitude regions may have a black and orange mimicry ring, contrasting with the lowland forms which display a yellow-tip tiger pattern. Similar variations occur with the orange-tip mimicry ring and the small white transparent mimicry ring. Here is a link to an important web-based study on the Perúvian Ithomiinae. These fragile-looking insects defend themselves with offensive chemicals, and a number of free-loading butterflies have converged through evolution to look like them, and so take advantage of their natural protection. The result is an extremely complex taxonomy. Ithomiinae genera are identified and separated by reference to their hind-wing venation.

The Lepidoptera populations are even more complex than butterflies. Various estimates have been made that suggest that 4-5 times as many moths exist in Perú as butterflies. Unlike the butterflies, they appear to be more evenly spread, with many species in the higher Andes. However, they are far less studied and much less is known about them.

Anyone out at night in the warm humid areas with hear the 'vroot-vroot' sound of the hawkmoths as they weave their way through the night's aerial traffic. They are important pollinators, fertilizing up to a hundred flowers in the course of a single ten minute foray. Day-time hawk moths compete for nectar with humming birds, some of which are roughly the same size. Plants that have evolved for moths are generally white to pale yellow - as with many cactuses, for example, whilst those with red flowers, and particularly those with trumpet-shaped, downward pointing red flowers, are bird pollinated.

Other insects and invertebrates are extremely evident in the tropical nights. Crick-crack beetles call, crickets and cicadas whistle, trill, shriek and buzz through the night. Groups of these may strike up on one tree, and then "pass the ball" to another group elsewhere. The result, in the dark of the jungle, is of a huge shrieking object hurtling past your head. The evolutionary advantages of this are obvious - where does a predator go? Trees can be lit up by luminous insects, often flashing in phase so that the entire tree blinks on and off.

The least welcome of these night travellers is the mosquito, which can and does carry malaria in much of Perú. (And dengue, and yellow fever.) Sandflies carry leichmaniasis. The coffee plantations have a small biting insect that can be seen when it is flying to attack by its bright yellow head. These insects dig out a plug of flesh and can leave workers arms dripping blood. There are also extremely large spiders (several species), centipedes of prodigious size and scorpions. Ticks of all sizes abound in the jungle, and the least likable of these (to the author's view, anyway) is a tiny reddish species which climbs up into the groin area and then buries itself in your flesh. This shotgun-pellet like lump itches fiercely for at least three months. Long garments, insect repellent such as DEET and regular inspections are recommended.

Huxley remarked that "the good Lord must have an inordinate fondness for beetles", and around 20-30% of all animals are indeed species of beetle. Perú has beetles that cut leaves and beetles that eat fruit, subterranean beetles and black plagues of beetles that darken the sky and settle on the coastal crops to devour them. The number of species seems inexhaustible and the collection of them has barely begun.