Caterpillar growth spurt

The other day, I admired how lush (beautifully green) my butterfly garden had become. My tall swan plants were all getting quite bushy, some with clusters of delicate white and purple flowers. So I arranged the plants (they are all in pots) and tidied everything, topped up the potting mix, swept up, and watered all the plants. It looked amazing. For a whole day!

Now, suddenly, I have a caterpillar population explosion! Again. This is the third time this summer I have found myself with more caterpillars than I can count. (It is probably the last time, as there are usually three generations of butterflies in a season.)

This is what happened. The other day, I had three or four enormous caterpillars. I admired them, photographed them, chatted to them about how fat they were. As well as those ones, there seemed to be about 20 medium-sized caterpillars, a bunch of little ones, and eggs here and there under leaves and so on. In the space of a few days, my enormous caterpillars gobbled a last meal and found places to pupate (turn into a chrysalis), while the medium-sized ones became fat, and all the little ones got bigger too. Now they’re all more noticeable and easy to see on the plants. And it seems as though they appeared from nowhere!

The other reason they’re more noticeable now is because they have stripped the leaves off several of the smaller plants, so there’s nowhere for them to hide. And they are noticing each other. They seem to eat even faster when there are a lot of them together, probably in case the leaf they’re eating is their last meal!


Am I obsessed with monarchs, or is it just a rumour?

It was only 15 months ago (Nov 2012) that my family and I moved to the town we live in now, on the Kapiti Coast of New Zealand. This is only my second butterfly season. And yet, people tell me I'm obsessed, and maybe a little bit crazy!

Where we lived previously, which was an elevated, windy area, we saw very few butterflies. The most frequent of those we did see was the red admiral, a beautiful but small, native butterfly.

A red admiral butterfly

When we arrived in Kapiti (at the end of the NZ spring), I was immediately captivated by the large, bold butterflies that fluttered around our flower garden, looking for tasty nectar. I must surely have seen monarch butterflies previously, as the colour and pattern of their wings were familiar, but I was surprised by how big they were and by how frequently they visited. My kids, aged 3 and 6 at the time, were also delighted by the butterflies.

I was keen to encourage more butterflies into the garden and to provide learning opportunities for the kids. So, in January, after some research into what monarch caterpillars eat, I went to the local garden centre to get a couple of swan plants (the main type of milkweed we have in NZ). I had a vision at that time of my two little plants growing into large bushes, with cute, stripy caterpillars and green-and-gold chrysalises hidden amongst the mass of leaves, and orange-and-black butterflies fluttering around contentedly.

I soon learnt how naive I was!

I planted my two swan plants in the garden, with plenty of room to grow, and waited for the butterflies to visit. Within a couple of days, however - as well as seeing the butterflies fluttering around and laying their eggs - I spotted two lovely, medium-sized caterpillars that seemed to appear from nowhere (but must have already been on the plants when I bought them).

The kids and I observed these first two caterpillars daily, as they fed on the swan plant leaves and grew bigger and bigger. We saw some tiny new caterpillars appear too, and we thought they were cute! When the time came, both of the original caterpillars left the plants, and we discovered one had formed its chrysalis on a nearby shrub (we never found the other one). Then, in early February 2013, I photographed my first newly emerged monarch butterfly, still drying its wings on the shrub.

My first butterfly I raised in my garden

Meanwhile, the tiny caterpillars grew, and more hatched from the eggs, and suddenly my swan plants were overrun with caterpillars. Ten tiny caterpillars don't eat much, but ten medium and large ones do! I bought more swan plants, then more, and each was quickly stripped of its leaves, so that only the stalks remained. And, as each large caterpillar wandered off to pupate (form its chrysalis), more tiny caterpillars took its place. My earlier vision of a butterfly garden with bushy, green swan plants was fast becoming a distant dream!

At that stage, I decided to rotate the swan plants. This involved keeping the plants in their pots, and letting the caterpillars have free rein on some plants, while I kept others aside, away from the hungry caterpillars and the egg-laying butterflies. As each plant was stripped, I would replace it with a fresh plant or one that had regrown some leaves. This generally worked well, but there were some challenges!

At first, I was keeping my reserve plants in my greenhouse, with the door open to allow airflow, but butterflies found their way in. I fashioned a mesh curtain over the doorway, but not before I had a small second population of caterpillars in there. The caterpillars on the plants didn't seem to mind the heat of the greenhouse, but, after a run of hot weather in March, it became too hot for them to successfully pupate. I moved the largest caterpillars out, and brought the remaining chrysalises into the house. This chrysalis was on the edge of the weedmat, so I snipped a piece off to bring the chrysalis inside.

A chrysalis that had formed in my greenhouse

Another challenge arose when the food ran out and, for a time, the local gardening shops ran out of swan plants. I found out that caterpillars over a certain size (2cm long) can eat raw pumpkin when swan plants are in short supply. So I added thin slices of this to their menu.

Rescuing chrysalises and managing the diet of caterpillars were the beginning of my home office doubling as a home for monarchs. Soon, it wasn't uncommon to find me hunting for missing caterpillars under my desk, chasing newly eclosed butterflies around the lounge, or peering into my camera to try to capture a moment in the amazing monarch life cycle.

I ended the 2012/13 butterfly season with 15 stalks that had once been swan plants (and they did not all recover), caterpillar poo on my desk, and empty chrysalises on my office wall. I had spent many hours managing caterpillar feed, counting and hunting for lost caterpillars, nurturing plants, squashing aphids, and staring through the viewfinder of my camera waiting for something to happen.

After a long wait, I captured this butterfly eclosing in a (time-lapse) series of images

But I had also laughed at caterpillars munching ferociously, jostling with each other as they fought over a leaf, and wriggling quickly across the hot concrete path (see video?). I had been transfixed watching butterflies emerge from their chrysalises, dry and test their wings, and take their first flight. I had released them into the garden and watched them fly away. And, to top it all, I had learnt a lot about monarchs through photographing them. (Like the scales on the butterfly's wings at the top of this post.)

So, instead of being put off, I was hooked. This season (2013/14), I upped my game. I raised some swan plants from seed, so I wouldn't run out of plants, and enclosed an area of our courtyard with windbreak mesh as a "butterfly area". The mesh will hopefully protect the caterpillars from predators, and protect the swan plants from both the wind and from laying butterflies when I already have enough eggs and caterpillars. It will also give the caterpillars a sheltered place to make their chrysalises.

It's a long way from perfect, but I feel that my vision of a garden filled with nectar flowers, lush green swan plants, and, of course, fluttering butterflies is just a little bit closer now.

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