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Click on each picture to see a larger view We have a number of milkweed plants under the cover of a net to protect the Monarch Caterpillars from wasps. You might think the net would prevent the female butterflies from laying eggs on these plants - but no. Some of the plants have grown tall and are now touching the net and so the female butterflies flutter over and around the netted plants, then land and lay eggs on, or as near to, the leaves as they can. It's amazing to watch the female butterfly crawling around on the net, sensing out the leaves underneath, then depositing eggs on them. Even through the tiny holes of the net, they manage to lay an egg on a leaf.
Click on each picture to see a larger view.... As our Summer begins in New Zealand, the female Monarch butterflies start their rounds of the swan plants to lay eggs. These Monarchs will have over-wintered in clusters, in trees, until the warmth of the sun activates their wings into flight.
Because of the huge predator risk from Asian Paper wasps, Praying Mantis, Ants, Shield Bugs, Earwigs and more, Monarch eggs and young caterpillars are particularly needing care. I collect the Monarch eggs and allow them to hatch indoors. I then transfer the newly hatched caterpillars to a swan plant (still indoors) and leave them on that until they are approximately half their eventual full size. At that point I transfer them to our outdoor swan plant enclosure to complete their caterpillar life cycle. There have been instances where Monarch eggs I have collected, have not hatched. That has been disappointing, however I understand there can be a variety of reasons why this might happen.
When my Monarch eggs do hatch their tiny caterpillars, it is a real thrill every time. Just look at the lovely iridescent sheen and tiny grooves on this Monarch Butterfly egg. It is about 1mm in size and the fine details cannot be seen by the human eye. The egg begins to darken when the caterpillar inside has matured enough to emerge. The first thing the tiny caterpillar does, when it's out, is to eat the skin of its egg. Our Northland, New Zealand, 2015-2016 Monarch season is underway. Having said that it wasn't my intention to start things off for a little while yet, however the Monarchs clearly had other ideas. You see, our swan plants (milkweed) are not yet large enough to sustain the caterpillars through to being butterflies, so I wanted to let them grow larger before allowing the Monarchs to lay eggs on them. We had a few small plants coming along in the garden, so I set them under the mosquito net so that butterflies could not lay eggs on them until I felt the plants were large enough to sustain the caterpillars. They are such voracious eaters, once they begin to grow larger, and plants soon end up with no leaves. At the time I placed the plants under cover there must have already been eggs on them that I hadn't noticed, so now they have all hatched and we have caterpillars. Yesterday I moved a tiny caterpillar, that I found on an outside swan plant, onto one of the plants under the mosquito net. Imagine my surprise to see at least 10 growing caterpillars already on the plants. OK, so I am in for an exercise in managing the plants, and somehow finding more when the caterpillars grow bigger, nevertheless I'm happy to see them already growing well. Let the season commence. Click on each picture to see a larger view.... Small caterpillar is into it's 3rd instar. It is now a lot more lively and almost 20mm long. My photo shows it finishing off a leaf that it began eating last night. Instars are the different stages Monarch caterpillars pass through, shedding their skin between each stage, until they reach a maturity that allows them to form their chrysalis. Monarch caterpillars eat only milkweed leaves. The leaves contain a white sticky sap that is a mild poison. Its bitter taste warns away many animals and insects that try to eat the plant. Certain insects however, including monarch butterfly larvae, are reasonably immune to the toxin. The clever caterpillar nips the main vein of a leaf, at the point where the leaf attaches to the stem of the plant. This drains away the majority of the toxic sap before the caterpillar feeds. As the caterpillar grows, its body accumulates the glycosides, making it unpalatable to predators. The yellow-black caterpillar colouring gives a warning to predators that the caterpillar is toxic. Unfortunately this doesn't deter the Asian paper wasp from successfully preying on the caterpillars in New Zealand and almost wiping out many Monarch caterpillar groups. Tiny caterpillar is also doing well and now at 2nd instar stage. It's about 10mm long now and, as you can see, its Monarch caterpillar colouring is becoming more prominent. To me it looks as if all tiny caterpillar does is sit all day. Upon checking this, I found it to be correct because apparently 2nd instar caterpillars don't actually eat a lot - perhaps a leaf or two a day. Very tiny caterpillar is growing well, too, and I'll show it to you in another post. Right now it's still so tiny that I have trouble finding it on the leaves - but it is there. As for the two eggs? Well they are both now quite dark, so it's anyone's guess if they'll hatch or not. I'm hoping. In New Zealand the main food for our Monarch Butterflies and Caterpillars is the Swan Plant Gomphocarpus fruticosus. Many of us grow swan plants in our gardens to encourage visits by Monarch Butterflies and to ensure more eggs are laid. In schools, children learn about the metamorphosis of the Monarch on it's amazing journey from egg, to caterpillar, to butterfly. The 'swans' on the swan plant are actually the seed bags and, when the seeds are mature and ready to be sown, the swan splits open to allow the seeds to fall out. Each seed is attached to a small, gossamer parachute, allowing it to float on the wind to its position of germination. "Milkweed or the Asclepiadoideae is a large family of plants with only a handful available in NZ. It is the host plant for the Monarch butterfly, which lays its eggs on the plant, and then the caterpillars begin to eat the leaves. It is named for its milky juice, which contains alkaloids, latex, and several other complex compounds including cardenolides. Some species are known to be toxic. However, do not get the plant family confused with plants such as dandelion, sow thistles, portulaca and Euphorbia species etc. – all of which also have a milky sap. Milkweed originates on two continents – the African and the American continents. The species that come from Africa were renamed ‘Gomphocarpus’ by Kew Gardens botanists. The American species are known as ‘Asclepias’, but all are members of the Asclepiadoideae family." >>>This information is from Monarch Butterfly NZ Trust) .....click here to read more >>> "In New Zealand the favourites are (The) Swan Plant (Gomphocarpus fruticosus), (The) Giant Swan Plant (Gomphocarpus physocarpus) and Tropical Milkweed - Bloodflower (Asclepias curassavica).
Other members of the Milkweed family (Asclepias spp) are eaten however there are only a few of these in New Zealand like the Common Milkweed (Asclepias syriaca) and Swamp Milkweed Asclepias incarnata. If your not in New Zealand, then the 'best' Milkweed is Butterfly weed (Asclepias tuberosa). Note: Butterfly weed (Asclepias tuberosa) can be grown in New Zealand, but it cannot be imported for fear of it becoming a invasive weed as it spreads by underground roots. So this is a rare plant in New Zealand, not helped by the fact it won't seed easily." One of the Monarch Butterfly eggs hatched today.
I noticed the egg was changing colour (it darkens), yesterday, and this morning the tiny caterpillar emerged. You can see it in my photo, above, with the remains of its egg. It's about 2 mm long at this stage. The usual process is this. "The eggs are laid on milkweed plants. They hatch into baby caterpillars (larvae). It takes about four days for the eggs to hatch. The baby caterpillar doesn’t do much more than eat the milkweed in order to grow. After about two weeks, the caterpillar will be fully-grown and finds a place to attach itself so that it can start the process of metamorphosis. It will attach itself to a stem or a leaf using silk and transform into a chrysalis. - See more at: http://www.monarch-butterfly.com/#sthash.oEYLHHaQ.dpuf" At this very late stage in the season, with our weather now quite cold, their survival isn't a given. If this tiny one does survive, its processes will be slower than usual. This is because, in the cold, the caterpillars become quite sluggish. So, the first step (egg hatching) has taken 7 days, when it would usually take 3 or 4 days. Right now, our tiny caterpillar is on a milkweed leaf, on a milkweed stalk I've placed in our lounge. When you pick the stalks, just smash the end of the stalk section a little, to allow it to suck up the water and stay fresh. I find the stalks last quite a long time, this way. Stay tuned and I'll keep you posted on Tiny's progress. Having recently moved house, to a different area in the north of New Zealand, I've been pleased to see a few Monarch Butterfly eggs on the swan plants.
This has been our holiday house, until now. Now it's our permanent home. I have been growing swan plants here, for the Monarchs, for several years. Unfortunately the huge wasp population in the area has ensured that no caterpillars are given a chance to grow past the first instar, before they become prey to the wasps. Because we've previously only been here for a couple of days at a time, (say every 6-8 weeks), there's not been an opportunity to really care for the Monarchs here. Now that we're here full time, I have a better chance to bring them all to butterfly stage. I've noted that, with our weather coming into Autumn, there are not so many wasps around at the moment. Having said that, I spotted a slightly larger caterpillar on a swan plant 2 days ago and knew I needed to get it under cover and safety from the wasps. Because we're still unpacking after the house move, it took a day to find the caterpillar castle. Wouldn't you know it? When I went out to the plant to get the caterpillar yesterday morning (and I had seen it there only 2 hours before) it had gone. Wasps!!! I searched the plants and found 3 eggs and they're now safely inside the caterpillar castle, waiting to hatch. We'll just have to wait and see what happens. I'll keep you posted. |
AUTHOR
Julie Vause
Opua, New Zealand. Keen butterfly photographer and raises Monarch Butterflies for release. " I'm crazy about butterflies and enjoy sharing the beauty and wonder of their transformations." VIDEO
Monarch Caterpillar emerging from egg
Click on video to enlarge
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