The butterfly farm

Butterflies
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Of all the insects, none elicit pleasure and curiosity more readily than butterflies. Like the abundance of verdant mountains and beaches, butterflies are ever present during one's visit to Costa Rica. There is nowhere one goes, whether a 3,000 meter volcanic summit or the arid plains of Guanacaste where butterflies are not present.

Costa Rica is unusually blessed by the diversity of it's butterflies. There exists about 20,000 butterfly species worldwide. Of these, about 1,000 or 5% can be found in Costa Rica.


An Outline of Butterfly Physiology

Butterflies are insects. By definition, all insects posses six legs and three body segments: head, thorax and abdomen.

The three most salient features of the head are the antennae, the eyes and the proboscis.

The antennae are used for balance in flight and olfactory sensation. Butterflies possess fragile wings. The wings can wear easily through normal use. They can also be badly damaged by predators which when attacking the butterfly grab only the wing rather than the body. Despite the loss of even the majority of their wing surface area, a butterfly will continue to be able to fly and navigate. They can do this because of the sense of balance afforded them by their antennae.

The antennae are also useful for smell. Female butterflies release pheromones (like a perfume) into the air. The male butterflies of many species can detect the pheromones from as far away as 2 kilometers (over a mile). Depending on the concentration of the pheromones, the male will be able to find the female to mate with her. It's worth noting that some species of moths are sensitive to the presence of the females' pheromones up to five kilometers (about three miles) distant.

The eyes of butterflies are large spherical structures. These are compound eyes consisting of thousands of hexagonal shaped omatidea. Each omatidea, or miniscule sensor, is directed at a slightly different angle from the others. Collectively they are directed in every direction -- up, down, forwards, backwards, left and right. Because of this, butterflies are able to see in virtually every direction simultaneously.

There is a price to pay for having an exceedingly small brain and omnivision. Butterflies cannot focus their vision as what they see is at best a blur. Furthermore, they are sensitive to only the three most basic features of vision which would be light, color and motion. Butterflies can distinguish night from day. They might distinguish color along a very narrow band of the light spectrum. Hence a butterfly might see and feed from the nectar of a purple flower but be oblivious to the red flower nearby. Butterflies are also sensitive to movement. When you try to catch a butterfly with your hand, it won't think, "Here comes Billies' hand". It would however be aware that something big out there is moving, getting closer and it's time to fly.

Butterflies do not have teeth or mandibles. Rather, their feeding mechanism is a long double barreled tube called a proboscis. Because they feed through what is essentially a double barreled straw, butterfly diets are exclusively liquids. The preferred diets will vary considerably depending upon the butterfly species. While people generally think of butterflies as feeding from the nectar of flowers, other common diets include mud, cow dung, water and tree sap.

People often ask if butterflies are important pollinators. The answer is, with some important exceptions, no. Bees are the pollinating workhorses of the world. For those species that are pollinators the pollen will stick to the proboscis or legs and be deposited involuntarily on the next flower visited.

The thorax, the middle body segment, connects the butterflies' appendages -- the six legs and four wings. The butterflies' ears, tight membranes similar to a human eardrum are also located here. Though it cannot be seen, these membranes have hairs just under them. When a sound wave hits the membrane, the membrane vibrates and touches these hairs. When stimulated, the hairs send a message to the brain indicating the direction and distance of the sound from the individual.

The reproductive, respiratory, circulatory and digestive systems are located in the abdomen. Since liquids are the only thing that enter the butterfly's body, liquids are the only thing that are excreted. The anus is located at the end of the abdomen and is generally well concealed.

A butterfly's circulatory system is relatively simple. The heart is a pump attached to a long tube that extends from the abdomen to the head. The blood is pumped through this tube and released into the tissues. Through a pressure gradient, the blood seeps through the tissue back to the abdomen. There it is sucked back into the heart and pumped forward again.

In a butterfly, there is no transportation of oxygen in the blood. Butterflies have valves called spiracles along either side of their bodies. Some of these spiracles, located mostly along the abdomen, allow oxygen to enter. Other spiracles exhale carbon dioxide. In this way oxygen will enter the body directly. Once inside, there is a network of tunnels similar to the network of veins in the human body. Oxygen will travel directly to where it is needed and pass into the tissue.

Reproduction

The only goal in life for an adult butterfly is to reproduce. The males look for females to inseminate. The females lay eggs.

Within the males' abdomen are the sperm producing organs. When the male mates, a set of "claspers" at the end of the abdomen will open and clamp down on the female's abdomen. Butterflies mate facing in opposite directions with their abdomens attached.

The penis enters the female at the same location where the eggs come out. When the male ejaculates, the semen enters a small storage pouch inside the females abdomen. After mating, the female has about 100 eggs inside her and a pouch full of the male spermatozoa. Once gravid, she will perform a kind of self-fertilization. When she places an egg on the hostplant, as the egg is passing out of her ovipositor, it will pass this pouch. At that instant, one spermatozoa will fertilize the egg and determine its sex. When the egg is first placed on the leaf, it was fertilized less than a second before.

A typical female butterfly will lay about 100 eggs in her lifetime. Some species lay their eggs gregariously (in clusters). Other species lay their eggs individually on widely dispersed plants. One school of thought argues for "survival in numbers" while the other takes the perspective, "don't put all of your eggs in one basket". Both approaches are valid, but only just sufficiently to ensure the survival of the species.

Of the 100 or so eggs that may be laid, only 2% should be expected to survive to become healthy adult butterflies. This figure is reasonable since in the aggregate one egg will replace the female and the other the male. The other 98% will fall by the wayside in the course of their development as eggs, larvae, pupae and emerging adults.

The reasons for this high mortality rate are several. The most important causes include climatic conditions (wind, drought and rain); diseases caused by virus and bacteria; and predators.

Larvae Stage

Larvae, being insects, have six legs, and although less pronounced than the adult, three body segments -- head, thorax and abdomen.

The larva have mandibles for chewing their food. The mandibles must be strong to break though the leaf and crush it. This is in contrast to the adult which can only feed on liquids. Bear in mind that the larval host plant has nothing to do with the adult's liquid diet.

The eyes of a larva serve for little more than distinguishing day from night. Because caterpillars need to be as inconspicuous as possible from predators, most are nocturnal feeders. During daylight hours they remain motionless in discreet corners of their hostplant.

Underneath the head are glands which exude a liquid which when exposed to the air forms silk strands. The silk strands can be useful for three reasons. First, they secure the larva to the surface they are walking on. Second, some species use the silk as an escape route. For example, when an ant attacks a small larva, the larva may drop off of the leaf and dangle from the thread in midair. Third, the silk will be used to form a "button of silk" from which the prepupa will attach itself to the underside of the leaf where it will hang.

The thorax is a short segment of the larva. It is distinguished by being immediately behind the head and possessing the three pair of true legs on the underside. When later transformed to the adult butterfly, the wings will extend from the area directly above the true legs.

The abdomen, consisting mostly of the digestive system, represents the largest segment of the larvae. Indeed, the abdomen may represent 80% of the body.

On the underside of the abdomen are a number of prolegs or "sucker-feet". This is a misnomer as the prolegs do not have suction cups at all. Rather, they are equipped with thousands of tiny hooks (very much like velcro) which assist with walking. As the larva lays down a sticky silk pad, the hooks on the prolegs will firmly grasp the silk. In this way larvae may attach themselves securely to whatever surface they may walk on no matter how sheer.

Along the sides of the abdomen one may find a series of spots. These are the spiracles -valves extending the length of the larva's body which allow the larva to breath.

Larvae, rather than having internal skeletons have exoskeletons. As the larvae grow, they must shed their skins just as snakes and shell fish do. This process of shedding the exoskeleton or skin is called molting. Virtually all larvae molt 4 times and each time they do so they will form a new "instar". The word instar refers to the stage of development of the larva. When a larva emerges from its egg it is a first instar larva. Larvae molt four times and pass through five instars. At the end of the larva's fifth instar it will have reached its full size and will form the prepupa. Inside the larva are all the parts of the butterfly. There is no complete breakdown of the larva and reformation to a butterfly. There is merely a specialization of body parts. The larva as a basic butterfly with additional parts to allow it to behave like a caterpillar. These additional parts would be suction feet, strong mandibles, a long body, and an enormous stomach.

The larval stage is the only stage of butterfly development where the organism grows. The larva will grow from the size of a tiny egg to the proper size for the adult. The growth rate is phenomenal. If a normal 7 pound human baby were to grow at the same rate as a Monarch larva, in just one short month that baby would be the size of a London double decker bus and weigh many, many tons.

Pupa Stage
When the larva reaches full size it stops eating and empties its stomach. You may notice that the pupa is about half the length of the larva. This is because about half of the larva is stomach. When the pupa forms, the larva stage is over and the parts it had are no longer necessary.

An adult butterfly does not need a large stomach because it only drinks small amounts of liquid. When the pupa later forms, the organism will consume the larval stomach to get energy to carry it through the dormant pupal stage. This is why the pupa is much shorter.

Pupae cannot fly, bite, sting or run away if discovered by a predator. They are practically helpless. Their principal means of defense is to blend in with their surroundings and remain inconspicuous. Without exception they are either brown, grey or green -- colors that hide very well in nature. Many of the pupae that one sees, with little or no imagination, can resemble things found in nature such as dried leaves, broken branches, fruit, and even the heads of venomous snakes.

The different parts of the butterfly undergo transformation to assume their new responsibilities as a butterfly. The process can take from a week to several months, although 10 days to two weeks is the most typical gestation time. When the adult butterfly emerges from the pupae, the wings will be wet and extremely malleable because they have been folded up to fit within the pupa.

The wing has a lamination around it that will begin hardening about half an hour after emerging. For this reason butterflies must hang upside down upon emergence. They need the help of gravity to pull the wings down into their natural position. If the wing gets caught on a branch and doesn't stretch out, it will stay like that forever. Most likely, this butterfly will not be able to fly. It will not be a contributing member of its species and will promptly die.

Relationship to Plants
Having mated, the female butterflies lay their eggs on the leaves and stems of particular plants. Upon emerging from the ova (egg) the larvae (caterpillars) will proceed to eat the leaves of the plants they were laid on. These plants are called host plants.

The relationship between any given butterfly species and it's host plant(s) is very specific. Some of the butterfly - host plant relationships for some common Costa Rican species are as follows.

Butterfly genus Host plant Butterfly genus Host plant
Parides sp. Aristolochia Papilio cresphontes Citrus
Battus polydamus Dione juno Passiflora
Anteos chlorinde Cassia Agraulis vanillae
Phoebis sp. Dryas iulia
Hamadryas sp. Dalechampia Heliconius sp.
Adelpha fessonia Randia Caligo sp. Musa, Heliconia
Papilio thoas Piperaceae Danaus plexippus
(Monarch)
Asclepias
(Milkweed)

People from all parts of the world often wonder, "What happened to the butterflies that we saw when we were children?" They are gone. As mankind cultivates the land, builds roads, houses, shopping centers and butterfly exhibits, he is fundamentally changing the landscape. Forest habitats are destroyed. So too are butterfly hostplants which are generally taken for useless weeds. So as we "progress", butterfly populations and wildlife in general regress.
Butterfly Defense Mechanisms

The list of butterfly predators is long. Suffice it to mention just ants, spiders, wasps, parasitic wasps, parasitic flies, birds, rats, toads, lizards, praying mantis, snakes and monkeys. There is little that would not like to eat a butterfly in one or another of its life stages.

Butterflies have developed many ways to protect themselves from their predators. We could divide them into 2 simple groups: good tasting and bad tasting. A butterfly that is good tasting is one that is regularly consumed by large predators like birds, snakes and lizards. A bad tasting butterfly is avoided by large predators due to its undesirable taste.

Bad tasting butterflies are colorful as adults and have toxins in their bodies that make the predator sick. The predator once having suffered the consequences of consuming such a butterfly will easily remember the bright color of the wings. It will know from that time on to avoid that color pattern. Although one butterfly will be killed from such an encounter, many more will live.

Good tasting butterflies are butterflies that, when eaten, are agreeable with the consumer and most defend itself accordingly. There are two ways to do it.

To be good tasting and bright is dangerous for an appetizing butterfly. Therefore the good tasting species camouflage themselves by being dull colors.

Mimicry is another effective defense. It is used by brightly colored species that are also good tasting. Their bright color patterns have evolved to appear like those of the poisonous butterflies. One example is the orange and black colored Viceroy which is strikingly similar to the poisonous Monarch. A predator that's experienced a monarch would never again venture consuming another orange and black specimen.

Female butterflies are programmed to know where and when they will lay their eggs. The males program is to mate with the female at the right time so he has to follow the same pattern.

Lets look at this starting with non migratory butterflies. A female hatches out of the cocoon and her program says to mate and begin laying eggs right away in the immediate location. Every female of this species has this program. They will quickly seek a male, mate, and lay their eggs on the hostplant.

A migratory butterfly has a different program. The big question is where does this program come from? Also, what triggers the running of the program which, in turn, makes the butterflies leave their present location and head for another. It could be climate conditions , or temperature, or an internal clock that sends them on their way.

For most of the rainy season, the butterflies of the Pacific coast have a program that says lay your eggs in the same area where you hatched. So, the butterflies live their lives in the same place. At the end of the rains, the females that come out have a different program that says "seek out the rains and lay your eggs there." Off they go to the Atlantic slope and there they will stay until the rain return the following year. Essentially, they are searching for the ideal climate to reproduce themselves.

Now for the Monarchs. The monarch feed on milkweed. The milkweed needs warmth and moisture to grow. At the end of the summer in southern Canada and the northern United States, Monarchs come out of the cocoon and their program says "winter is coming here soon, you must seek warmth and lay your eggs next spring". They seek warmth by flying down to Mexico. They arrive in November. There are literally millions of them. They will sit on these trees until springtime when the first milkweed of the new year is coming out along the Gulf of Mexico. When that happens, they will fly there, lay their eggs, and die.

Realize that butterfly just lived 9 months and flew 4-5 thousand kilometers. If that's what it takes for the species to exist, that's what it will do.

These eggs on the Gulf of Mexico will mature and fly to the central (north-south) of the United States. Because their journey is not as long, they don't live as long. They will fly for a couple of weeks, lay their eggs at their destination and die.

The next generation will do the same. Notice that they are moving up the states at the same pace as spring and summer. They are following a constant climate. This generation comes out at the end of the summer and they have the same program as their great grandparents did. They fly all the way back to Mexico where they will wait out the next spring.

The Monarchs of Costa Rica are non-migratory because their need for a warm climate is always satisfied. They live three weeks and lay their eggs in the local area.

Differences Between a Moth and a Buterfly
What is the difference between a moth and a butterfly? There isn't a single defining characteristic that defines a moth versus a butterfly. Rather there are a number of characteristics. The following is a list of most of the differences:
  1. A butterfly flies by day, and a moth by night. There are some day flying moths and butterflies that fly at dusk.
  2. A butterfly always has a feeding mechanism (proboscis), whereas a moth often does not. These moths simply do not eat as adults as they have done all their eating as larvae.
  3. A butterfly rests with its wings closed and a moth lands with them open. A notable exception are the butterflies of the Hamadryas genus (Nymphaliinae) that always land with their wings laid flat.
  4. A butterfly forms a pupae hanging. A moth forms a cocoon, usually on the ground.
  5. The antennae of a butterfly are straight and club-like. The antennae of a moth vary greatly but are usually brush like with a great deal more surface area.


This information is supplied courtesy of Joris Brinckerhoff who established the first commercial butterfly farm in Latin America.

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