Sunday, March 23, 2008
From larva to moth via silk coccoon.
In their own country, silkworms would live on mulberry trees as this is their only source of food and their waste would drop to the ground. In captivity, you need to provide a clean and comfortable alternative. A shoebox with plastic wrap is an easy option. Keep the box at room temperature but out of direct sunlight. Puncture the plastic wrap with small air holes, but make sure they're not big enough for your silkworms to escape! You may need to place the shoebox above a moat of water to stop ants getting in!
About six weeks after the eggs have hatched they will start to spin coccoons. At this stage you need to add some sticks, curved bark or cardboard rolls to the shoebox so the caterpillars have edges to attach their silk to.
The caterpillars feed mainly on mulberry leaves. If you obtain eggs before the mulberry trees have developed leaves then you can put the eggs "on hold" in the fridge. If they hatch anyway, you can feed them on carefully washed lettuce leaves.
When your caterpillars are young, tear the mulberry leaves into smaller pieces so there are lots of edges for them to eat along.
You will need to clean the box out every day as the silkworms eat a lot of leaves and that creates a lot of caterpillar poo! As they grow larger they will moult so old skins need to be thrown out too. The bigger the caterpillars get, the more leaves they eat. Eventually, you will need to feed them every few hours. But you can plan ahead and pick lots of mulberry leaves which last several days in a plastic bag in the fridge.
To clean the box without damaging the delicate caterpillars pick up the leaves they are on rather than picking up the caterpillars themselves.
About six weeks (or up to 47 days) after hatching from eggs the caterpillars start to spin their coccoons. These are made from one long strand of silk about 800-1200 metres long and this process can take 3 to 6 days.
In this picture you can still make out some of the features of the caterpillar as it spins its coccoon within the silk anchors.
Parts of the caterpillar
Silworms have a head, a thorax and an abdomen. The head has simple eyes and tiny feelers. The silk is made by two glands near the mouth. The thorax has three segments and each of these has a pair of legs. Along the abdomen there are false legs that silkworms use for gripping and balancing. The whole abdomen has 10 segments.
The moth will hatch about 15 days after the coccoon is finished. The moths cannot eat or fly and they only live for a few days which is enough time to mate and lay eggs so that the cycle can start all over again.
Activity - Watch an online slideshow about silkworms. What extra facts does it contain?
Activity - Draw and label a silkworm or draw and label your own life cycle of a silkworm.
Monday, March 10, 2008
One area was set aside as an "Explore nature area". This contained a large feely box with seedpods, banksia cones, sticks, smooth pebbles and a stuffed bandicoot! Students were encouraged to explore by touch and try to identify and distinguish the contents. In another area, feely boxes contained one item only and students were encouraged to feel the object and try to draw what it was without looking.
This area also contained magnifying glasses and objects to study up close including bug boxes and a cat skull.
There were books and posters identifying birds and binoculars to help spot some. There were also bird nests set up as a puzzle where students had to match the nest materials to the type of bird or the kind of location it would be found. For example, a nest made of sheep's wool might come from a farm and a nest of paperbark might be from the Wolli Valley.
There were also structured activities for classes to undertake including paperbark craft; wax resist, a stone game and a smell game. Following are the instruction sheets for these.
Traditional Aboriginal people used paperbark for many different things:
- coolamons (carrying baskets for food and water);
- food wraps and plates
- toys like balls.
Yr 6 crafted Aboriginal-style coolamons and balls out of paperbark and string.
Make your own!
Paperbark ball – wrap bark around scrunched newspaper and tie with string. NB: Aboriginal people would not have had newspapers or string. What would they have used?
Paperbark carrying basket – make a small canoe shape. Tie the ends together with string.This bark was gathered outside the National Park. It is not OK to take things from inside the Park no matter how small. You may be moving a rare seed and stopping it from growing. You may be spreading an invasive weed.
You can take these bark creations back to your school or home. Try playing football or netball. Try carrying something in your basket.
Share your knowledge with others.
Sit the class in a circle on the grass. Choose a quiet, shady location.
Select roughly 6 pairs. The remainder can observe first then have a turn later.
One partner in each pair is blindfolded and then chooses a rock from the center. They examine the rock by touch for 3-5 minutes then put it back.
Their “seeing” partner must remember which rock it was. They should have a good look at it before it is returned.
The blindfolded person then has to remember how the rock felt and identify it by sight.
The class should take a sheet of paper and make impressions of natural textures: rocks; bark; leaves, seed pods, etc.
Paint over the wax drawing with coloured water to reveal the textures.
Or, simply use coloured crayons to create an impression directly onto the paper. See if you can find trees or rocks with different textures and capture the patterns on each half of one page.
Smells from nature
Encourage children to smell the hidden leaves and think about what they're smelling. Some questions to provoke thought. Is the smell:
- pleasant or unpleasant?
- strong or mild?
- from an edible plant or not?
- from a native plant or not?
- from a tree? bush? garden plant?
* Does the smell remind them of anything? A certain place or time?
* Do they recognize any of the hidden plants?
1. Pine or conifer tree.
2. Lemon-scented tea-tree (Leptospermum petersonii). Native tree.
3. Eucalypt leaves. Native tree.
4. Mint leaves from Ferncourt's herb spiral.
We acknowledge the traditional owners
of the land on which we live and learn.
We pay our respects to them for their care
of this land over countless generations.
We hope they will walk with us on our journey.
The guided walks covered different aspects of the built and natural environment. Older classes went as far as Turrella Reserve and Nannygoat Hill to the North or Illoura Reserve to the South. Younger classes explored the Bray Ave wetland, Paperbark Creek or the interesting features of Girrahween Park itself including a de-nutrification wetland.
Shelter under rock escarpments with evidence of smoke from Aboriginal cooking fires.
Turrella Reserve and Nannygoat Hill
Students walking to Turrella Reserve saw rock shelters used by the Bidjigal people and saw remnant vegetation that has been restored to how it might have looked in Aboriginal times. They saw paperbark trees used for Aboriginal huts, canoes, food wrapping and toys. They learned Aboriginal place names:
Girrahween = “place of flowers”;
Turrella = “reeds growing in water”;
Minnamorra = “plenty of fish”
Wolli = “camping place”
The Turrella Weir was identified as the divide between fresh water on right and tidal salt water on left. Different species occur downstream to upstream. Plants include mangroves, saltmarsh and casuarinas on the tidal side. Native fish such as Sea Mullet, Port Jackon Perchlets and Eels are found in the saltwater side. In the freshwater side there are various species of gudgeon.
Turrella Reserve had been wetlands full of reeds and subject to flooding then later Chinese market gardens but Council filled in the area to create parkland. It still functions as water bird habitat to some extent.
At Nannygoat Hill students observed the proximity of gardens to bushland, enabling the spread of weeds and exotic plants like “Mother of Millions”. They also learnt about stormwater issues: the streets here (Minnamorra etc) drain into Wolli Creek (so does rubbish) .
Illoura Reserve and Paperbark Creek
Students who walked towards Bexley found an area still needing much bush restoration and regeneration and saw the effects of garden plants becoming invasive weeds.
Bray Avenue Wetland was seen as a haven for birds; much bush regeneration has been undertaken and Canterbury council have made efforts to control stormwater.
Students observed a “no mow” area which allows native seedstock to grow where it belongs. These have been established by volunteer bush regenerators with the co-operation of Council.
- the proximity of gardens to bushland, enabling the spread/or dumping of weeds;
- the proximity of roads to bushland, enabling the dumping of truckloads of rubbish (roof tiles, washing machines, filing cabinets)
Stormwater issues were evident: the streets here Bray Ave, etc drain into Wolli Creek (so does rubbish)
European history: A road reservation relating to this stretch of land meant that the bushland was subject to years of neglect (compare to Girrahween Park which is well maintained by NPWS). Prior to the road reservation, Kings Farm existed (near Bexley end of track).
Students explore Paperbark Creek – a stormwater channel restructured by Council
Girrahween Park - De-nutrification wetland
"De-nutrification" is a big word! so lets break it down. We've all heard about nutrients and are often told about having nutritious food instead of junk food. Nutrients make things grow. They’re good if they’re in our food but not so good in our waterways.
Nutrients in our waterways make plants grow.
Too many nutrients make water plants grow too fast and too big.
Why is this bad?
Water gets oxygen from the air (waves and wind help stir it in).
Fish need that oxygen in the water.
BUT, if plants cover the water, they stop the oxygen from dissolving in the water, so fish die.
Rotting dead plants take even more oxygen out of the water.
HOWEVER, if we are clever, we can use this system to clean up our dirty water. We must simply keep the water flowing and harvest the plants to keep them from growing too big.
Look upstream from the bridge: Here we can see water flowing down from a stormwater outlet near the Earlwood shops. It’s bringing some pretty rich nutrients with it!
The reeds have been planted to eat up the nutrients and stop so much getting into Wolli Creek (downstream from the bridge).
So, de-nutrification is just a big word that means taking the nutrients out. This makes Wolli Creek healthier.
Wetlands: Natural and Constructed
Wetlands were long regarded as wastelands but are now recognised as important features in the landscape that provide benefits for people and other animals. Wetlands are home to an abundant variety of plants, water bugs, reptiles, birds, fish, frogs and mammals - they are considered to be 'biological supermarkets'. They are among the most productive environments in the world and form a link between our land and water resources.
Stormwater comes from urban areas after rain. As water flows across roads and other hard surfaces it can pick up pollution such as rubbish, chemicals and sediment. This polluted stormwater can be caught and filtered by constructed wetlands before it enters a waterway.
Friday, March 7, 2008
Blue Triangle Butterflies - flitting about in weeds behind Kindergarten.
Worldwide, there are 22,000 species in the Order Lepidoptera. Only 400 of these are butterflies (that’s just 2 per cent!). There is no simple foolproof way to distinguish between butterflies and moths, but try these methods:
· butterflies are brightly coloured and active by day, while moths fly by night.
· butterflies tend to rest with their wings held together above their backs, while moths tend to fold their wings like a tent over their backs.
· up close, butterflies have clubbed tips to their antennae, while most moths have feathered antennae.Butterflies : resting with wings together; antennae have clubbed tips
Moths: wings folded, tent-like; feathered antannae
Just to confuse matters there are others in the Order Lepidoptera which are neither butteflies nor moths. They are called skippers and grass darts! They are most easily recognised by a combination of flat and upright wings. They can often be seen on the flowering oregano in the herb spiral.
Adult butterflies may live from at least two weeks to six months, and everywhere in between. Life spans of some school species include:
- at least four weeks for the Cabbage White (Pieris rapa)
- at least five weeks for the Orchard Swallowtail (Papilio aegeus)
What do butterflies need?
Nectar plants alone do not help butterfly species to breed and survive, but may help you to see butterflies by attracting them to the garden.
Butterflies require both:
1. a host plant to lay eggs on; and
2. plants that provide nectar.
1. a host plant to lay eggs on.
Butterflies are extremely particular about plant choice. For example, silkworms will only eat mulberry leaves and no other plants.
The butterfly larvae will eat these specially chosen leaves when they hatch. The tiny caterpillars eat lots of leaves and will moult several times as they grow larger and larger. When fully plump they then spin their chrysalis or cocoon. Generally, the plants they feed upon are not permanently damaged and some may benefit from this gentle tip pruning.
2. plants that provide nectar for the adult butterflies.
Adult butterflies are particularly attracted to daisy-type flowers (eg native everlasting daisies) as these provide excellent landing platforms while the butterflies are feeding, although other flowers types are also visited. Colour and scent are also important factors. The curled proboscis reaches the nectar by uncoiling and dipping into various shaped flowers.
Curled proboscis of a Splendid Ochre - Trapezites symmomus (photographed in the Wolli Valley)
What do moths need?
Moths, on the other hand, are most active in the evening so coloured flowers are not important. They are often attracted to cream and white flowers as these show up well at night and are often fragrant, giving off a scent which is particularly strong at dusk and early morning and very effective in attracting moths to flowers from a great distance.
Some adults will never feed, or will require other food sources such as rotting fruit (eg tropical butterfly species), bird or animal droppings! or simply mineralized water (stream banks, mud puddles etc).
This Emerald moth was very well camouflaged against a Greek Basil leaf unlike the very plain brown moth on the same plant.
This Granny's Cloak Moth (left) was one of several hiding in the cool, dark tool shed while the small brown moth (right) liked to hide under sage leaves in the herb spiral.
Below is a very colourful Orange Spotted Tiger Moth on some flowering mint. See how the proboscis stretches into the flower to reach the nectar.
Attracting butterflies and moths to your garden
- Find out which species of butterflies and moths you have locally, and set about encouraging those
- Grow food plants for larvae to encourage females to lay eggs
- Grow food plants for adult butterflies with flowers rich in nectar, scent and bright colours
- Include night-scented flowers (often white) with strong sweet scent to attract moths
- Grow plants which flower at different times of year to provide a continuous food supply
- Ensure diversity in your garden layout, with a mix of shaded and sunny areas, areas providing shelter from winds, and preferably some 'wild' or untended areas where grasses and 'weeds' are allowed to run freely
- Avoid insecticides and other chemicals as much as possible and explore alternatives such as physical removal of pests, carefully timed removal, biological control, companion planting and 'friendly' organic sprays (pyrethrum leaves mixed with casuarina needles and garlic in warm water)
What threats to avoid or manage
While an adult butterfly may lay 300-500 eggs, very few will make it through to maturity. They are vulnerable at every stage of development:
- eggs (parastic wasps corrupt the eggs, ants carry them away; humans remove them);
- larval stages (larva are directly preyed upon by spiders, shield bugs, assassin bugs and ants; they are parisitised by Tachinid flies or Braconid wasps);
- adult butterflies (are preyed upon birds and frogs).
This moth, Cruria synopla, has no common name. Perhaps it should be called a "Bat Moth" because it likes to have its head towards the ground when it lands. It is pictured here on the Lemon-scented gum in the ELA.
Urban landscapes, including Sydney gardens, are capable of supporting a wide range of butterfly species. A combination of local Sydney plants for larval food and adult butterfly nectar needs can contribute to the maintenance of local and regional biodiversity of butterflies. Butterfly gardening provides an opportunity to help some species persist in otherwise sterile urban landscapes.
There is scope for increasing the diversity of butterfly food plants in our gardens, especially if we coordinate this with the other co-requisites of butterflies (sunshine, shelter from wind, water sources and freedom from pesticides). It is a very worthwhile challenge for native plant gardeners everywhere.
Appendix: Examples of food plants:
Acacia podalyrifolia (Mt Morgan wattle)
Acacia melanoxylon (blackwood)
Indigofera australis (native indigo)
Leptospermum juniperinum 'horizontalis'
Lomandra sp. (mat rush)
Olearia phlogopappa (daisy bush)
Parahebe perfoliata (speedwell)
Poa sp. (snow grass)
Westringia glabra (native rosemary)
Westringia longifolia (native rosemary)
Abelia x grandiflora (glossy abelia)
Achillea millefolium (yarrow)
Asclepias tuberosa (butterfly weed)
Buddleia davidii (butterfly bush)
Centranthus ruber (red spurred valerian)
Choisya ternata (Mexican orange blossom)
Cistus sp. (rock rose)
Dianthus sp. (pinks and sweet william)
Echinacea purpurea (purple coneflower)
Hebe sp. (hebe)
Helianthus annuus (sunflower)
Lathyrus odoratus (sweet pea)
Lavanadula spp. (lavender)
Melissa officinalis (lemon balm)
Monarda sp. (bee balm)
Myosotis sp. (forget-me-nots)
Origanum majorana (marjoram)
Philadelphus sp. (mock orange)
Salvia sp (sages)
Santolina sp. (lavender cotton)
Teucrium chamaedrys (wall germander)
Tropaeolum hybrids (nasturtium)
Valeriana officinalis (valerian)
For Moths (night-scented flowers):
Hesperis matronalis (sweet rocket)
Myrrhis odorata (sweet cicely)
Narcissus sp. (daffodils, jonquils)
Philadelphus (mock orange)
Attracting Butterflies to Your Garden
Author: Densey Clyne
Publisher: New Holland Publishers - rrp $23.95 IBSN: 1 8 7633 456 8
Distributor: CSIRO Publishing
Freecall: 1800 645 051
Plenty of information can be found via a Google search BUT… a word of warning: do not order seeds advertised on the Internet in webpages promoting butterflies. These plants are usually unsuitable for our native butterflies to breed on — and some have the potential to become serious weeds in Australian bushland.