Butterflies are able to utilize all of the food resources of the tropical rainforest.

All butterflies have a distinct larval stage, in which the butterfly exists as a jawed and usually plant-eating caterpillar, followed by a resting, non-feeding pupal stage.

Adult butterflies are fluid feeders. Some butterflies have less conventional feeding habits.

Some heliconids, long-winged South American butterflies, feed on pollen grains.

Monarch butterflies are attracted to pools of mammal urine, perhaps encouraged by the high nitrogen content.

Charaxes butterflies, native to Africa and Southeast Asia, feed on such large amounts of rotting fruit, feces and other decaying material that their abdomens become quite distended.

Most butterflies, however, feed at flowers. They usually sip small quantities of nectar.

Swallowtails are drawn to flowers not visited by other butterflies, in particular to red ones.

This is unusual since the sensitivity of insects is usually toward the ultraviolet end of the spectrum rather than the red.

Butterfly larvae are often specific in their choice of food plants.

The larvae of some species of Bematistes feed only on forest vines, particularly passion flowers.

Monarch butterfly larvae restrict themselves to milkweeds.

Butterfly Defenses

Many butterflies of the troical rainforest use their brilliant colors and remarkable patterns as a form of defense. . Particular patterns advertise the fact that a crea­ture is unpalatable. By trial and error birds have learn to associate these patterns with toxic or distasteful insects and avoid them.

Unpalatability in adult butterflies is usually linked to the feeding habits of the larvae. The larvae of many jungle butterflies feed on plants that contain harmful chemicals. The larva detoxify and store these chemicals in their tissues.

The sequestered compounds are carried on to the adults, rendering them unpalatable also.

Although the chemicals in the plants are of course designed to deter plant feeders, insects can quickly evolve the necess­ary enzymes to adapt to the plant's chemistry.

Toxic butterflies signal their unpalatability by their patterns. To take advantage of this, a number of different distasteful species have evolved the same basic patterns. This means that predators need less time to learn which species to avoid.

Batesian Mimicry

Some butterflies imitate the patterns of toxic butterflies, although they themselves are palat­able. This technique is known as Batesian mimicry, after the natural­ist Henry Bates.

There are many instances of butterfly mimicry in the tropical rainforest. One complex example involves a heliconid butterfly, Heiconius nattereri. The male and female have different wing patterns and there­fore have their own separate mimics

Butterflies and Passion Flowers

Coevolution of plants and insects is common in tropical rainforests.

Heliconid butterflies have had a long association with passion flower vines.

The butterfly lays its eggs on the passion flower. The larvae feed on the plant and acquire poisons from it which make them unpalatable to birds.

In the battle to deter the heliconids, new species of passion flower evolve, synthesizing new poisons in the proces. In turn, new heliconid species, which can detoxify the poisons, evolve. Many forms of both passion flower and heliconid result.

Heliconids adapt to detoxify only the chemicals of their particular passion flower and so are restricted to feeding on that species.

Passion flowers also try other protective devices.

Many have additional nectaries which are not inside flowers. Some of these nectaries attract ants which then defend the plant from egg-laying but­terflies.

Others look like heliconid eggs, so when a female heliconid lands on the plant, she is tricked into thinking that the plant is already heavily popu­lated.

Passion flowers such as the Costa Rican species Passiflora adenopoda, have hooked hairs which cover their surface. These hairs trap and puncture the heliconid larvae, who starve and bleed to death

Morpho Butterflies

Blue morpho butterflies, which live in the rainforests of South America, are known for their iridescent blue wings.

The wings are so brilliantly colored that aircraft pilots flying overhead have noticed them.

Male morpho butterflies travel in crowds, cavorting in the sunshine or patrolling extensive territories through the upper canopy and emergent layers of the tropical rainforest

Because these butterflies are so brightly colored, it is easy for predators to spot them. However, morphos are quick, adept fliers and are difficult to catch.

The fact that morphos are easy to recognize may even be an advantage when it comes to avoiding predators. Because attacks are usually unsuccessful, predators may learn that trying to catch a morpho is a waste of time and energy.