Monarch Butterflies

The monarch butterfly is a great fascination for gardeners, we just love seeing them flitting around our gardens during the summer months. Some become very worried when they don’t have these butterflies arrive in their gardens, at the expected time each year with no caterpillars on any of the many swan plants, they have specially planted out for them.There is even a Monarch Butterfly web site in New Zealand at where people can log into and participate in sightings and many other activities.

The Monarch butterfly (Danaus plexippus) is an interesting creature that is poisonous to birds and predictors because of its diet on the milkweed plant we commonly call the swan plant. (Gomphocarpus fruticosus) The caterpillars, having a diet of this plant, helps to
keep them safe from predictors and the same applies to the adult butterfly. If by chance a predictor was to eat either the caterpillar or butterfly it would become sick and then remember in the future to leave them alone.Large amounts of caterpillars on even a large swan plant will soon decimate the plant to the point where the plant has no foliage left and it dies. My recommendation to prevent
this is to place a small clear plastic bag over a small portion of the foliage at the end of one branch. Tied in such a manner so that no caterpillars can get to eat the foliage inside the bag. Punch very small holes in the bag so that the foliage can  breath and moisture can escape. By doing this it will save the plant and once the caterpillars have finished for the season the swan plant can regenerate for next summer. (Remove the bag when caterpillars are finished for the season). In the mean time you can, once the caterpillars have eaten all the other foliage, either purchase more swan plants to enable them to reach the stage of pupating (forming their cocoon) or you can take the caterpillars off the plant and feed them on pieces of pumpkin or cucumber till they reach their final stage.

Another problem that gardeners can have is insect pests such as aphids or mealy bug attacking the swan plant while there are caterpillars present.There is no chemical or safe sprays that can be used to control the pests without also killing the caterpillars. Generally speaking you need to control the pest insects by
squashing them till such time as the caterpillars have all pupated and then if there are no further eggs on the swan plant you can safely spray Neem Tree Oil for control. Also do not place any Neem Tree Granules anywhere near the root zone of the swan plant while the caterpillars and eggs are present.If mites attack the swan plant you an safely spray with Liquid Sulphur without harming the caterpillars.

I looked up the Internet and found some interesting facts on Monarch Butterflies which I will share with you:

How do you tell the male monarch from the female?. Males have a small spot on the inside surface of their hind wings that is not present in females. The ends of their abdomens also look different. Females tend to look slightly darker than males, and have slightly
wider wing veins.

How come only male monarchs have a big black spot on their wings?  These dots are made of specialized scales that, in some butterflies, emit a chemical used in courtship. Even though this chemical does not appear to be important in monarch courtship, the males still have the spots. The spots are much larger on close relatives of monarchs.

How many times do their wings flap in a minute? . About 5 to 12 times a second, so about 300 to 720 times a minute. (This is actually quite slow compared to many other butterflies.)

How do monarchs breathe?  Monarchs breathe through tiny openings on the sides of their bodies called spiracles. (The spiracles are in their cuticle, like our skin). The holes open into a system of tubes in their body (called trachea) that carry the oxygen all over
their bodies. They don’t have lungs.

Do monarch butterflies have brains?  Yes, they do. All insects have brains. Just like our brains, their brains receive messages from the rest of the body, and send messages to the muscles and other organs in the body. They are relatively smaller than our brains,
though. ( Likely there are some exceptions to this as I noted through my lifetime, my comment).

Can butterflies overheat if it gets too hot? . Yes! Butterflies of many species need to avoid extreme heat, and have many strategies for doing so. Monarchs retreat to shady places when it’s very hot.

Is it true that monarchs can only see one color? No, butterflies have the broadest visual spectrum of any known animals, and can see more colors that you can! They can see UV light, which humans can’t.

Are butterflies nocturnal or diurnal?  Diurnal.

Where do they go and what do they do at night?  They remain still at night, probably on vegetation like bushes and trees.

The life span of the adult Monarch varies, depending on the season in which it emerged from the pupa and whether or not it belongs to a migratory group of Monarchs. Adults that emerged in early summer have the shortest life spans and live for about two to five
weeks. Those that emerged in late summer survive over the winter months. The migratory Monarchs, which emerge from the pupa in late summer and then migrate south, (America) live a much longer life, about 8-9 months.

I hope that has given you a better insight to our much loved Monarch Butterflies.

Having a neat summer for a change has brought a problem for many gardeners and that is the number of insect pests such as leaf hoppers, whitefly and vegetable beetles that are ravaging our gardens. When one finds hundreds of these types of pests attaching our plants the plants will be suffering and in some cases will succumb and die.

A common problem is that we may be repeat spraying our plants for control but never seem to get on top of the problem. I had an example of this recently with leaf hoppers and discovered why when I decided to pull out an area of bracken ferns nearby. The ferns were covered in leaf hoppers, young fluffy bums and adults. By getting rid of this source or breeding plant I then was able to get control over my preferred plants.

If the breeding ground happens to be over the fence you either need to get permission to control there or just hang in with lots of reaped sprayings.

I had a lady call me the other day to say that everything was ok in her garden till the owner of the section next door decided to clear the vegetation to build. Within days all those pests that were living on the weeds and plants next door, invaded her gardens.

The safe way to maintain some sort of control is to place Neem Tree Granules on the soil in the root zone of plants and then to do repeat sprays, late in the day using Neem Tree Oil and Key Pyrethrum.Repeat sprays would be between every 3 to 7 days till the situation is under control or till the weather turns cold and nature knocks back the breeding cycles.

Just one of the things we gardeners have to face on a good summer.

22 comments on “Monarch Butterflies

  1. i think we have a monarch butterfly in the garden. When do they normally hatch?

  2. It probably is – they hatch around about now. slightly larger than your average butterfly – black and orange. Like the image at the top of the page.


  3. I will take a photo of the cocoon and then maybe when it hatches. I am hoping it will hatch?
    Could anything go wrong?

  4. Robert on said:

    Nothing is certain – your best bet is to make sure it does not get blown away – it should be fine – you can also talk to it nicely

  5. ok. It has a white spun appearance and it seems to have a head poking out – i hope it hasnt died already? It is attached to a vine. I will upload the photo and you can see.

  6. Annabele on said:

    Are monarch butterflies in Australia.

  7. Hi Annabele,

    yes they sure are – sometimes reffered to as Wanderer butterflies – see article here


    Tim Durrant

  8. Heather on said:

    Hello – I have quite a lot of caterpillars ready to pupae – will buy some more plants to feed them. Do I need to keep the plants (all in pots) in sheltered places at night because of the cold now its autumn? or dont they mind?
    Heather, New Zealand

  9. Hi, I have had two caterpillars on a plant and having been watching them grow daily. All of a sudden they have both disappeared. They have been on my terrace which is enclosed at night. They have not reached the stage of pupae. Could it be a spider?

  10. It could be one of many things, Kay. There are lots of predators that find Monarch caterpillars are tasty morsels. Assassin bugs, praying mantises – even ants. You can find out more about them on our website, at

    While people tend to think of Monarch butterflies as “good” and their predators as “bad”, if every Monarch egg survived to maturity, then the Monarchs would become a plague. Some of their eggs are destined to be food for other species – it’s only “natural”.



  11. Shynelle Houghton on said:

    This is more of a question about caterpillars, I Had a couple caterpillars in a container bringing them home from school to put onto my swan plants and i noticed them attacking each other, I had plenty leaves in the container so they shouldnt have been hungry!! When i put them onto the plants one of the caterpillars “feelers” had been bitten off buy another caterpillar and it eneded up dying. Is it normal for them to attack each other?

  12. Chris Hawken on said:

    I have had great success raising monarchs until last season when the swan plants became infested with yellow aphids. This year some plants have yellow and cream stripes appearing on new leaves – is this a virus? They are covered in eggs and caterpillars and I’m concerned that it may spread to all the plants

  13. Hi I have a swan plant which has heaps of caterpillers on it,. i am worried they are going to run out of leave. What can i feed them? or would i be best to buy another swan plant?

  14. I have too many monarch caterpillars for the 5 plants I have got. What can I do to help.The plants are destroyed in 2 days.

  15. You will find everything you need to know on this website.


    Tim D

  16. Judy Peteson on said:

    Hi. Could you please help us. We have a few swan plants in the garden, with plenty of butterflies flying around, laying eggs on them. This has been happening for some weeks now, but not a sign of a caterpillar. Do you know what the problem is?
    Thank you. Judy P

  17. i have none send them to christchurch lol

  18. no virus but when they turn yellow the leave drop off;yellow aphids r mongrels u need to spray them with hot sunlight liquid it kills them not while caterpillars r present though

  19. yes its normal its competition for food it always happens

  20. dont think so could be a hedgehog

  21. they r pretty hardy after about two years but they cant handle snow

  22. Steveandhelentaua on said:

    What do I do with the plant now that it is sovered in seed pods and the pods

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