Insects

 

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Insects and Arachnids

Needless to say insects and arachnids are everywhere in the rainforest. Most are harmless to humans, and only pose a possible threat in some cases when disturbed. The insects are among the most diverse and abundant groups in the rainforest. One particularly notable species that many who may have visited the tropics are aware of, are chiggers. Chiggers are mites. It is in the larval stage that the chiggers use humans as a host, burrowing into the skin at "pressure points" i.e. elastic waistbands. The best way to deal with chiggers is to avoid sitting in grass or on logs, and use insect repellent where clothing meets skin. If one has become a host to some chiggers, do not worry. There may be some discomfort from itching, but other than that the chiggers are relatively harmless.

Mosquitoes, while present in the rainforest, are not much of a concern. True, some of them do carry serious diseases such as yellow fever, malaria and other tropical diseases; and it is wise for the expectant traveler to inquire about inoculations or other preventative measures before embarking on a trip to the Amazon. Seasonal mosquito swarms are not common in tropical rainforests as they are in temperate areas. Immediately following sudden heavy down pours there may be increased mosquito activity, and these insects do tend to be more abundant in the rainy season than in the dry season. In temperate or artic zones where the mosquitoes life cycle is compressed into a few short weeks or months, the presence of mosquito swarms can be undeniable. In the tropics, some insect repellent, long sleeves and pants, and mosquito netting for sleeping are usually adequate.

Botflies are quite common in the Peruvian Amazon. Botfly eggs are transported to a host by a bloodsucking fly. The maggots hatch on the skin of the host and burrow inside; the host then acts as shelter and a food source as the larval botfly (Dermatobia hominis) matures. As the botfly grows, it turns under the skin of the host causing a tingling sensation from the tiny spines that cover the body of the larva. As the botfly grows so does the lesion on the host; this condition is called "specific myiasis". After an incubation period of 40-50 days the botfly emerges. If one wishes to eliminate this parasite before it emerges itself, one might try putting petroleum jelly on the lesion. The jelly obstructs the larvaís tiny breathing tube that remains outside of the skin. The larva will suffocate and then can be extracted from the host. Another suggestion is to tape a piece of meat over the lesion, the larvae will leave the host for the meat.

There are many different species of ants in the rainforest. Two species that most people have heard of are the Leaf Cutter Ants (Atta spp.) and the Army Ants (Eciton spp.). The Leaf Cutter ants are frequently seen carrying leaves across the forest floor, a more than significant feat considering it is comparable to a six-foot man carrying a 750 pound (338 kg) load at a remarkable speed over at least a few miles! The leaves are dropped into an underground nest where more ants chew the leaves and form them into pellets that are then inserted into a mass of leaf paste. A fungus grows on this mat; the fungus and leaf sap make up the antsí diet.

Although the movies may portray army ants as mass swarms devouring everything in site with no escape for anything in their path, this is hardly a reality. Typically army ants move at night. They are group predators and their prey consists of baby birds, small lizards, caterpillars and spiders. If you encounter a group of army ants during the day, simply step over them.

The lesser known but impressive bullet ant (Paraponera clavata) is a large tropical ant that delivers a particularly nasty sting and bite. These insects are one inch or more in length, tend to be solitary, and can be found anywhere from the forest floor to the trees. If a nest is disturbed it is believed they give off a chemical alarm; in addition the worker ants may emit a loud squeaking noise.

Spiders of course are not insects, but arachnids. For many people, spiders, like snakes, induce feelings of both fear and intrigue. There are a number of different species of spiders all generally referred to as tarantulas, and they are all non-aggressive towards humans. If one should accidentally get bitten, their bite is harmless to humans (unless you have an allergic reaction to the venom). The enemy of the tarantula is the hunting wasp, whose sting will paralyze the spider that is then used as food for the wasp larvae. If you would like to see a Tarantula while visiting the rainforest, take a flashlight out at night; these nighttime predators can usually be found not to far from their burrows in the ground.

Termites are an essential part of the rainforest. One can find their nests either attached to tree trunks or underground. The nests are composed of digested wood and termite fecal matter. Interestingly it is a protozoan that lives in the termitesí intestines that actually digests the cellulose from the wood. Without these intestinal fauna, the termites could not digest the wood. Although these protozoa enable the termites to digest wood, many topical trees are hard wood trees, possibly an evolutionary response to termite herbivory; some of the woods are actually poisonous to termites. The termites themselves have developed some interesting defenses against predators. The soldier termites emit a sticky substance that smells similar to turpentine which can be irritating to predators including the anteater. Termites are an essential part of the rainforest for decomposing wood; but they are also valuable because of their nests. As they abandon their nests, which they do regularly, the mounds are full of nutrients. As the mounds decompose they leave patches of high nutrient concentration in the soil. These areas are then prime spots for new tree growth. What a beautiful example of the circle of life!

The Lantern Fly (Fulgora laternaria) is one of the more unique looking insects. This creature has a long head that resembles a cross between an alligator and a lizard. Its wingspan is about five inches and when perched on a tree, it resembles a lizard. The Lantern Fly gets its name from folklore that speaks of an insect with a bioluminescent head, however its head does not glow in the dark!

Butterflies and moths are common in the rainforest; one of the most spectacular is the Menelausí Blue Morpho (Morpho menelaus). This butterfly displays a deep blue color on its upper wings; they are cryptic when their wings are closed on the ground or on a tree. This beautiful butterfly can usually be seen around streams and in sunlit areas. Its diet consists of a variety of plant species.

The Owl butterfly (Caligo memnon) is distinguishable by a prominent eye-spot on the base of each wing. This otherwise cryptic species flashes the underside when disturbed. Researchers frequently find specimens with injuries (probably from bird beaks) in the area of the eye-spots; they hypothesize that these markings draw the predatorís attention, and thus the attack, to that area, allowing the butterfly to at least survive the encounter.

There is a group of butterfly species, commonly called antbutterflies, which follow army ants. These butterflies are members of the Nymphalidae family and subfamily Ithomiinae. It is only the females that follow the ants, to feed on the droppings of the antbirds, which provide the butterflies with a nitrogen source essential to make eggs.

Heliconid butterflies are among the most beautiful butterflies in the tropics. Their brilliant colors seem almost iridescent, making them highly visible to predators. As with the poison arrow frogs described elsewhere, the vibrant coloration serves as a warning to predators. Specifically, the bright colors of the heliconid butterflies serve to warn predators of their unpalatable taste.

 


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