Monday, May 14, 2012

The Dragonfly Life Cycle

The Dragonfly Life Cycle

Dragonfly Life Cycle
A dragonfly has a life span of more than a year, but very little of that life is actually as an adult dragonfly. There are three stages of the dragonfly life cycle, the egg, the nymph, and the adult dragonfly. Most of the life cycle of a dragonfly is lived out in the nymph stage and you don’t see them at all, unless you are swimming underwater in a lake or pond with your eyes opened, of course.

The Egg Stage
Dragonfly Laying Eggs in the Water 
A male and a female dragonfly will mate while they are flying in the air. After two dragonflies mate, the female dragonfly will lay her eggs on a plant in the water, or if she can’t find a suitable plant she will just drop them into the water.

The Nymph Stage 

Dragonfly Nymph

Once the dragonfly eggs hatch, the life cycle of a dragonfly larva begins as a nymph. A nymph looks like a little alien creature. It hasn’t grown its wings yet and has what looks like a crusty hump hanging onto its back. Dragonfly nymphs live in the water while they grow and develop into dragonflies. This portion of the dragonfly life cycle can take up to four years to complete, and if the nymph cycle is completed in the beginning of the wintertime, it will remain in the water until spring when it is warm enough to come out.

Dragonfly nymphs live in ponds or marshy areas because the waters are calmer than in a stream or river. Sometimes they can be found in the calmer backwaters of rivers, too. Dragonfly nymphs may eat smaller dragonfly nymphs as they develop.

The Adult Dragonfly Stage 

Dragonfly Laying Eggs in the Water

Once the nymph is fully grown, and the weather is right, it will complete the metamorphosis into a dragonfly by crawling out of the water up the stem of a plant. The nymph will shed its skin onto the stem of the plant and will then be a young dragonfly. The skin that the nymph left behind is called the exuvia and you can find the exuvia still stuck to the stem for a long time after the dragonfly has left it.

Once the dragonfly leaves the exuvia it is a full grown dragonfly. The dragonfly will hunt for food and begin to look for a mate. Once the dragonfly finds a mate, the female will find a body of calm water that will be a good place to lay her eggs, and the life cycle of the dragonfly begins all over again. Adult dragonflies only live about two months.

Life Cycle ,Ladybug

The Life Cycle of a Ladybug

The ladybug life cycle is not much different from the life cycle of a butterfly . The ladybug goes through the same four stages as a butterfly, the egg stage, the larvae stage, the pupa stage, and the adult ladybug stage. You know what adult ladybugs look like, but you wouldn’t even recognize them before they get to that final stage of their lives.

Egg Stage

Articles covering the life cycle of a Ladybug including fun facts, anatomy and more.
Ladybug Eggs with some Larvae Newly Hatched
Female ladybugs lay their eggs on the underside of leaves. This is to protect them from being seen by flying predators as well as from the weather. A mother ladybug will lay from ten to fifteen eggs in one place and she will make sure that it is a place where the babies can find food when they hatch. The ladybug eggs look similar to yellow jellybeans, except that they are tiny. The next time you are in the park in springtime, carefully look under some plant leaves and see if you can pick out some ladybug eggs, but don’t touch them because you could kill the babies.

Larvae Stage

A Ladybug Larva
ladybug larvae
Once the eggs hatch, the larvae will come out and start looking for something to eat. They will look for tiny mites or aphids and they should find plenty because the mother found the perfect leaf to lay her eggs under because of the abundance of food for the larvae to find. Newborn larvae look sort of like tiny alligators. After only a few days, the larvae will be large enough to begin to molt (shed their skin), and they keep molting for as long as they are growing. You can find the molted skins on leaves if you look very hard.

Articles covering the life cycle of a Ladybug including fun facts, anatomy and more.
Ladybug Pupa on a Leaf

Pupa Stage

After a couple of weeks of growing, the larvae will start to change into something that looks like a shrimp. It will find a leaf to attach itself to and it will seem to fall asleep for a few days, but it is not sleeping at all. During the pupa stage, the larvae are going through a metamorphosis into a ladybug.

Adult Ladybug Stage

What does a newly emerged ladybug (one that just hatched out of the pupa) look like?

Articles covering the life cycle of a Ladybug including fun facts, anatomy and more.
Adult Ladybug
When the metamorphosis is complete, the skin of the larvae will split open and the full grown ladybug will emerge, but it still won’t look like the ladybug that you know so well. It will look soft and pink or very pale for a couple of hours until its shell becomes hard. As the shell hardens it also gains pigment, which causes the ladybug to become bright red.

Raising Ladybugs

Some people likeraising ladybugs in ladybug farms similar to an ant farm or a worm farm. They do this because they love ladybugs and so that they can watch the wonderful transformation of the ladybug life cycle. Lots of teachers have ladybug farms. If your teacher doesn’t have one, you should ask him or her to get a ladybug farm for the classroom.

Life Cycle of Aquatic Insects

Life Cycle of Aquatic Insects

Photo of an adult mayfly (McKenzie Page) Mayfly adult
What is a nymph? How about larvae? Are your thinking about pixies and maggots? Well, you are partially correct. Chances are you already are familiar with the adult forms of many aquatic insects.


The aquatic insects comprise the bulk of benthic macroinvertebrate communities in healthy, freshwater streams. These insects are mostly in their immature form and live their adult life on land, sometimes for only a few hours. Most aquatic insects can be divided into two groups: ones that develop through complete metamorphosis, and ones that develop through incomplete metamorphosis.
Photo of adult riffle beetle (Illinois Ecowatch Network)
Riffle beetle larvae and adult
Metamorphosis is the change that occurs during the organism's development from egg to adult. Some aquatic insects develop through complete metamorphosis, which consists of four stages. These immature insects are called larvae and the do not resemble the adults, and in fact, may look grossly different. During the pupae stage, the organisms inhabit a "cocoon-like" structure where the transformation from larvae to adult occurs.
Figure 1
Complete Metamorphosis: eggs - larvae - pupa - adult (McDonald et al. 1990) Incomplete Metamorphosis: eggs - nymph - adult; several growing stages called instars (McDonald et al. 1990)
Incomplete metamorphosis has three main stages of development (except for the mayfly that has two winged growing stages). These immature insects are called nymphs and they undergo a series of molts until the last decisive molt transforms the organism into an adult or imago in mayflies. There is no intermediate pupae stage where transformation occurs. The nymphs resemble the adults closely except for wing development.

Life Cycle of Mosquitoes

There are over 2500 different species of mosquitoes throughout the world of which 150 species occur in the United States. 52 species occur in California, and 19 species occur in Alameda County. In the course of the District's operation about 10 species are commonly found in the County. Eight of the species account for over 99% of complaints from the public.

Each of the species has a scientific name that is latin, such as Culex tarsalis. These names are used in a descriptive manner so that the name tells something about this particular mosquito. Some species have what is called "common names" as well as scientific names, such as Anopheles freeborni, the "Western malaria mosquito".

All mosquitoes must have water in which to complete their life cycle. This water can range in quality from melted snow water to sewage effluent and it can be in any container imaginable. The type of water in which the mosquito larvae is found can be an aid to the identification of which species it may be. Also, the adult mosquitoes show a very distinct preference for the types of sources in which to lay their eggs. They lay their eggs in such places such as tree holes that periodically hold water, tide water pools in salt marshes, sewage effluent ponds, irrigated pastures, rain water ponds, etc. Each species therefore has unique environmental requirements for the maintenance of its life cycle.

The feeding habits of mosquitoes are quite unique in that it is only the adult females that bite man and other animals. The male mosquitoes feed only on plant juices. Some female mosquitoes prefer to feed on only one type of animal or they can feed on a variety of animals. Female mosquitoes feed on man, domesticated animals, such as cattle, horses, goats, etc; all types of birds including chickens; all types of wild animals including deer, rabbits; and they also feed on snakes, lizards, frogs, and toads.

Most female mosquitoes have to feed on an animal and get a sufficient blood meal before she can develop eggs. If they do not get this blood meal, then they will die without laying viable eggs. However, some species of mosquitoes have developed the means to lay viable eggs without getting a blood meal.

The flight habits of mosquitoes depend again on the species with which we are dealing. Most domestic species remain fairly close to their point of origin while some species known for their migration habits are often an annoyance far from their breeding place. The flight range for females is usually longer than that of males. Many times wind is a factor in the dispersal or migration of mosquitoes. Most mosquitoes stay within a mile or two of their source. However, some have been recorded as far as 75 miles from their breeding source.

The length of life of the adult mosquito usually depends on several factors: temperature, humidity, sex of the mosquito and time of year. Most males live a very short time, about a week; and females live about a month depending on the above factors.

Mosquito Life Cycle

The mosquito goes through four separate and distinct stages of its life cycle and they are as follows: Egg, Larva, pupa, and adult. Each of these stages can be easily recognized by their special appearance. There are four common groups of mosquitoes living in the Bay Area. They are Aedes, Anopheles, Culex, and Culiseta.

Egg : Eggs are laid one at a time and they float on the surface of the water. In the case of Culex and Culiseta species, the eggs are stuck together in rafts of a hundred or more eggs. Anopheles and Aedes species do not make egg rafts but lay their eggs separately. Culex, Culiseta, and Anopheles lay their eggs on water while Aedes lay their eggs on damp soil that will be flooded by water. Most eggs hatch into larvae within 48 hours.

Larva : The larva (larvae - plural) live in the water and come to the surface to breathe. They shed their skin four times growing larger after each molting. Most larvae have siphon tubes for breathing and hang from the water surface. Anopheles larvae do not have a siphon and they lay parallel to the water surface. The larva feed on micro-organisms and organic matter in the water. On the fourth molt the larva changes into a pupa.

Pupa: The pupal stage is a resting, non-feeding stage. This is the time the mosquito turns into an adult. It takes about two days before the adult is fully developed. When development is complete, the pupal skin splits and the mosquito emerges as an adult.

Adult: The newly emerged adult rests on the surface of the water for a short time to allow itself to dry and all its parts to harden. Also, the wings have to spread out and dry properly before it can fly.

The egg, larvae and pupae stages depend on temperature and species characteristics as to how long it takes for development. For instance, Culex tarsalis might go through its life cycle in 14 days at 70 F and take only 10 days at 80 F. Also, some species have naturally adapted to go through their entire life cycle in as little as four days or as long as one month.

The following pages show a typical mosquito egg raft, larva, pupa, and adult, and explains more about each stage.

Mosquito Egg Raft

Culex mosquitoes lay their eggs on the surface of fresh or stagnant water. The water may be in tin cans, barrels, horse troughs, ornamental ponds, swimming pools, puddles, creeks, ditches, or marshy areas. Mosquitoes prefer water sheltered from the wind by grass and weeds.

Culex mosquitoes usually lay their eggs at night. A mosquito may lay a raft of eggs every third night during its life span.

Culex mosquitoes lay their eggs one at a time, sticking them together to form a raft of from 200- 300 eggs. A raft of eggs looks like a speck of soot floating on the water and is about 1/4 inch long and 1/8 inch wide.

Tiny mosquito larvae emerge from the eggs within 24 hours.

Notes: Anopheles mosquitoes lay their eggs singly on the water, not in rafts. Aedes mosquitoes lay their eggs singly on damp soil. Aedes eggs hatch only when flooded with water (salt water high tides, irrigated pastures, treeholes, flooded stream bottoms, etc.).

Mosquito Larva

Mosquito larvae, commonly called "wigglers" or "wrigglers", must live in water from 7 to 14 days depending on water temperature.

Larvae must come to the surface at frequent intervals to obtain oxygen through a breathing tube called a siphon. The larva eats algae and small organisms which live in the water.

During growth, the larva molts (sheds its skin) four times. The stages between molts are called instars. At the 4th instar, the larva reaches a length of almost 1/2 inch.

When the 4th instar larva molts it becomes a pupa.

Note : Anopheles are unlike Culex and Aedes larvae since they do not have a breathing tube, they must lie parallel to the water surface in order to get a supply of oxygen through a breathing opening.

Mosquito Pupa

Mosquito pupae, commonly called "tumblers", must live in water from 1 to 4 days, depending upon species and temperature.

The pupa is lighter than water and therefore floats at the surface. It takes oxygen through two breathing tubes called "trumpets". When it is disturbed it dives in a jerking, tumbling motion and then floats back to the surface. The pupa does not eat.

The metamorphosis of the mosquito into an adult is completed within the pupal case.

The adult mosquito splits the pupal case and emerges to the surface of the water where it rests until its body can dry and harden.

Mosquito Adult

Only female mosquitoes bite animals and drink blood. Male mosquitoes do not bite, but feed on the nectar of flowers.

Aedes mosquitoes are painful and persistent biters, attacking during daylight hours (not at night). They do not enter dwellings, and they prefer to bite mammals like humans. Aedes mosquitoes are strong fliers and are known to fly many miles from their breeding sources.

Culex mosquitoes are painful and persistent biters also, but prefer to attack at dusk and after dark, and readily enter dwellings for blood meals. Domestic and wild birds are preferred over man, cows, and horses. Culex tarsalis is known to transmit encephalitis (sleeping sickness) to man and horses. Culex are generally weak fliers and do not move far from home, although they have been known to fly up to two miles. Culex usually live only a few weeks during the warm summer months.
Those females which emerge in late summer search for sheltered areas where they "hibernate" until spring. Warm weather brings her out in search of water on which to lay her eggs.

Culiseta mosquitoes are moderately aggressive biters, attacking in the evening hours or in shade during the day.

Anopheles mosquitoes are the only mosquito which transmits malaria to man.

Chicken Life Cycle

Chicken Life Cycle

"The Egg" by Jack Prelutsky
If you listen very carefully, you'll hear the chicken hatching.
At first there scarcely was a sound, but now a steady scratching.
And now the egg begins to crack the scratching starts to quicken,
As anxiously we all await the exit of the chicken.
And now a head emerges from the darkness of the egg,
And now a bit of fluff appears, and now a tiny leg,
And now the chicken's out at last, he's shaking himself loose,
But, wait a minute that's no chicken...
Goodness, it's a goose.
What is a bird?
A bird is the only animal that has feathers.  Also, all birds have bills, have wings, and lay eggs. 
What are the stages of the chicken's life cycle?
Eggs:  A hen lays eggs in a nest. Some eggs have an embryo inside.  An embryo will grow into a chick in 21 days.  The mother hen must keep the egg warm.  The egg's hard shell protects it while it grows.  The baby bird will use an egg tooth on it's beak to hatch out of the egg.  This can take a full day!
Chick:  The chick is wet when it hatches from its egg.  It has feathers called down.  The down will dry fast.  Also, chicks can walk right away.  They like to eat seeds, bugs, and worms.  Chicks grow more feathers in about 4 weeks. A comb grows on the chick's head and a wattle grows under the chick's beak.  Chicks resemble their parents from the time they hatch and as they grow.
Chicken:  Chicks are fully grown into chickens in six months.  Female chicks grow up to be hens.  Male chicks grow up to be roosters.  The hens will lay more eggs. 
Click the thumbnail below to see a picture of the chicken life cycle.

The Life Cycle of a Salmon

The Life Cycle of a Salmon

The life cycle of all salmon follows a series of stages as it develops from an egg to an adult fish. Each species of salmon has its own 'rules' that determine the length of time each stage has and also when these fish return to the rivers to spawn. Therefore each of the pacific salmon species are unique. The information illustrated below shows the stages each salmon goes through.



During spawning, eggs are deposited by the female in redds (a gravel depression scoured out by the adults with their tails). Milt (sperm) is then deposited from the male salmon to fertilize the eggs and begin a whole new generation. Depending on water temperature eggs will take between 6 to 12 weeks to hatch. The tiny black spots you can see in the photo are the eyes developing. These are what we would call eyed eggs.
Salmon Alevin


Alevin are newly hatched fish. They derive their nourishment from the yolk sac of the egg from which they were born. Nourishment is provided by the yolk sac for several weeks. They stay down in the river gravel until the sac is absorbed. Once the sac has been absorbed the 'fry' begin to emerge from the gravel and swim freely looking for food for the first time.
Salmon Chum Fry


Once an alevin's egg sac is absorbed, the fish has to find food for itself. This stage is called the fry stage. The fry will swim about feeding on tiny invertebrates and on the carcasses of the spawned out adults. Fry instinctively hide, deal with river currents, learn to school together and many other survival skills.
Salmon Smolt


Fry live in fresh water anywhere from just a few days to two years depending on the species. Smolting is a physiological change which when completed enables the fish to live in salt water and not absorb the salt into its blood stream. Once a fish turns into a smolt it is ready to begin its migration down the river and into the ocean where it will spend the next phase of its life.
Adult Coho in Ocean

Ocean Life

During their ocean phase Pacific Salmon are widely distributed over the North Pacific and Bering Sea. Most will have extensive migrations from one to five years (depending on the species). This is where the salmon do most of their growing and gain weight quickly. The Ocean phase is the phase which we know the least about and it seems that the early part of the ocean phase is very important for overall fish survival.
Spawning Salmon


When the adult fish have finished growing in the ocean they then seek out the rivers in which they were born to spawn. The fish undergo physical changes from bright silver to much darker and sometimes boldly coloured mature adults. The energy the fish gained in the ocean is put solely into the production of eggs (females) and milt (males). The mature adults pair up and start the process all over again of making a redd and laying eggs. This is where the cycle ends for one but and begins for another. The Seymour River has several viewing opportunities for salmon such as Coho, Pinks, Chinook and Chum. Visit the hatchery during spawning season - updates will be put on the Home page as we start to see fish spawning in the Seymour River.

Life cycle summary

Fish Life Cycle

Life Cycle of Bees

Life Cycle of Bees

This is the life cycle page. A bee is like a butterfly because it goes though several stages in its life. Keep reading to find out about a bee's life.


A queen lays soft white eggs in the comb. The egg stage takes place during days 1 through 3.


In three days, the egg hatches into a larva. Workers feed it bee milk and bee bread. It spins a cocoon around itself. The larva stage takes place during days 4 through 9.


In the cocoon, the larva turns into a pupa. It now has eyes, wings, and legs. It looks more like a bee. This stage is during days 10 through 23, depending on the type of bee it will become.


This is the final stage in a bee's complete metamorphosis. It is full grown. The bee chews its way out of the cell. It becomes an adult on days 16 through 24, depending on what type of bee it is.