the green butterfly


rain forest in Costa Rica

I have a thing for butterflies – or more specifically for their erratic flight patterns and metallic shades. Even the cabbage white butterflies living in my backyard (and letting their young eat my cabbage), have this hint of iridescence giving the white of their wings a hint of shine. Sadly, my temperate climate doesn’t offer the full spectrum of butterfly bling that’s out there (but does save me from spiders with jaws strong enough to break my skin (mostly)).

A recent post I read about fear and spiders in Costa Rica, got me thinking about my own trip to the country years ago. Jungles are exotic – at least to me since I’ve always lived at mid-latitudes. They’re both fascinating and frightening, I certainly wouldn’t want to be out there alone at night. This trip was one of the few opportunities I’ve had to wander through jungles (and I didn’t get eaten!).

Out hiking, I spotted an iridescent green butterfly just off the trail. The green was colour of a granny smith apple and glittered with every flap the butterfly took. After getting my camera ready, I followed the insect through the undergrowth (mildly foolish, I know). I got lucky and it let me get close.


The best shot I got of the green butterfly. If anyone can identify it, please let me know.

The iridescence in a butterfly’s wing (or dragonfly’s body, or a rooster’s tail, or even an oil slick on water), isn’t from a pigment. Instead an optical trick is required. In the butterflies case, the surface of the wing are covered in scales with a depth of one quarter the wavelength of blue (or green) light. Then the light reflected off the surface is augmented by the light reflected off the back surface giving the insect that fabulous iridescent effect.

I’ve written more on the physics behind iridescence here and here.

a cool shot

the ferris wheel at the midway

My work sent me to a fall fair last weekend (that’s where I took the photo), we had a booth so I spent two days chatting to the people passing by. I certainly see the value of engaging the public about the science we do and I don’t mind answering people’s questions.

Since I’m an introvert, by the time I got home Sunday night, I was exhausted. Even though I wanted to do more writing, my evenings have been spent flopping on the couch watching bad action movies. More coming soon.

Playing with fire


A candle on earth

I remember making candles when I was a kid. We filled empty food cans with paraffin wax – the stuff that comes as a opaque block about the size of a deck of cards. The cans were then put into a bath of boiling water until all the wax melted. A few crayon stubs were added to each can, creating an array of colours. I tied a thick piece of cotton string, destined to be the wick, around a pencil for easy dipping.

Next, dipping (the messy part) could begin. With each dip another layer of wax clung to what was already there, increasing the diameter of the candle-to-be. I rotated through the colours, creating what must have been gaudy candles. When the candle was thick enough to stand on its own, the fun part began: we could light them.

A flaming match held to the exposed end of the wick has enough heat to vaporize wax within the wick and react with the oxygen in the air. Within moments a teardrop-shaped yellow flame flickers to life. The heat from the candle’s flame melts the wax, and the melted wax is drawn up by the wick, sustaining the flame. At its hottest, a candle’s flame can reach 1400 degrees Celsius.

Heat vaporizes the wax creating a gaseous cloud where combustion takes place. Combustion is a series of chemical reactions converting molecules into new combinations – an inefficient process resulting in heat and light. Light, along with its cousin heat, signify the release of excess energy.

Compared to an incandescent light bulb, a candle produces 100 time less light, which is probably why candles are now mostly used to set moods, conduct rituals and provide light in power outages. I don’t often light candles, after all they are one of the leading causes of residential fires and they put soot and chemicals into the air I breathe. But, when I do have a reason to light a candle, I enjoy watching the flickering flame – I find something about it quite mesmerizing.

In my mundane earth existence, when I light a candle the hot gases formed are less dense than the air around them, and so they rise in a process of natural convection into the familiar teardrop shape. This natural convection hinders complete combustion, so soot forms which makes the flame yellow.

Out in my funky futuristic (imaginary) spaceship, where there would be no gravity, natural convection wouldn’t occur, and I would get a perfectly spherical flame. And, the flame would require ventilation or it would smother itself as its temperature would be evenly distributed. (here’s a good, but slightly inaccurate video) On the plus side, the combustion would be complete – so soot would not form. The flame would be bluer and more efficient.

Another effect of gravity on a candle’s flame is the flickering. The frequency squared of a flame’s flickering is proportional to the force of gravity over the diameter of the candle. Meaning that a candle with a smaller diameter would flicker at a faster rate than one with a larger diameter. So a candle on another planet (with different gravity) would flicker at a different rate than the same candle on earth.

A candle on my spaceship wouldn’t flicker at all (I would have to be mesmerized by its pretty spherical blueness instead).

note – this post was originally published back in May 2010 (here)

another note – I downloaded the image from here

Plant Profile – Irish Poet Tassel Flower


Irish Poet Tassel Flower (Emilia javanica)

I thought I’d profile a plant I grew this year solely because of a pretty picture in a seed catalog. Most of what I grow is edible in some form as I’m trying to put my urban yard to good use. There are a few exceptions like cosmos and sweet peas – flowers that I grew up with and feel sentimental about. There are other perennial flowers I’ve been given which add nice colour. But, the Irish Poet Tassel Flower (Emilia javanica) was completely new to me and I’ve not seen it grown around here (if my neighbours were growing it I likely would have asked to harvest a few seeds). The rather cumbersomely named Irish Poet Tassel Flower is also known as just Tassel Flower and a red version I’ve not seen is called Lady’s Paint Brush.

The bright orange puff that makes up a Tassel Flower gives the illusion that Beaker from the muppets is lurking in my flower bed (I’m not the only one who thinks about muppets – I recently met a woman who named her rooster Beaker). The flower is kinda silly and orange is my husband’s favourite colour so I ordered the seeds (from here).


Looking down on a Tassel Flower

I had success both from plants I started early in a cold frame and from seeds I planted directly into the soil. This plant is a sun-lover and has flowered continuously since early summer without any deadheading making it a winner in my mind. Even though deer regularly visit my fortified food forest, not once did this flower get munched on (the local deer are not picky – they even ate all the potato greens). Tassel Flowers are potentially poisonous if ingested but the pollinators seem to like them. I also strongly suspect that Tassel Flowers will reseed themselves, which I’m okay with.


An Irish Poet Tassel Flower gone to seed

Native to tropical Africa, Tassel Flowers were imported to England in 1799. During Victorian times they were known as Flora’s Paintbrush I don’t know when they got their current name. The flowers are about thumbnail sized at the end of a long stock, potentially making them a nice cut flower (I always forget to do this). The leaves are thick and green, I found the entire plant quite attractive and dense enough to hide the mulch. Since they are an open pollinated variety, I collected seeds when the flower turned into a dried puff of parachutes like a dandelion does. I’ll be growing Irish Poet Tassel Flowers again next year.

Things to do with chives plus a surprise


Chives past their pretty stage

As I’ve mentioned before, I have happy chives. Come early spring, these chives burst forth with new growth before most everything else. All it takes is a few moments outside with scissors and I’m ready to sprinkle my scrambled eggs with chivy goodness. I’ve gone so far as to stop growing green onions and use chives instead. Unfortunately (or perhaps fortunately), since they tend to spread, the amount of chives currently growing is way more than the amount of chives I use. So what should I do with my excess chives?

Digging all but one small clump up and adding them to the compost pile appeared to be the winning solution for a while – but I never got around to it (occasionally laziness pays off).

With their puff balls of purple on stalks of green, chives do have their moment of beauty. And as soon as they bloom, they are swarmed with pollinators which I consider a good thing. But, their flowers don’t last long, soon they dry out and resemble yellowed tissue paper – not so pretty.

A few days ago I went out to dead head the chives with the hope that I’d get more harvestable leaves. With the first flower plucked, little black chive seeds spilled out (into my strawberry patch so no doubt I’ll be weeding out new chive plants later). I have no need to start chives from seed as they easily divide into new plants, but come mid-winter I like to grow sprouts and chives make lovely sprouts. Their seeds are only viable for a year or so and often hard to come by for sprouting purposes.


The black chive seeds are ready to be shaken out

By the fist-full, I shook the flowers over a large bowl resulting in 75g of seeds (ironically, my last bag of chive seeds for sprouting was 75 g). Now I’m set for a winter of chive sprouts – and I’m still hoping they will put out new green growth for me to harvest.

Now for the surprise:


A baby goldenrod crab spider amongst the chive seeds

It also turned out that the chive patch was home to lots of little spiders. I kept having to stop shaking chive flowers to rescue spiders out of the bowl, then I spotted an adult – a goldenrod crab spider laying in wait for an unsuspecting honey bee. She was one of the prettiest spiders I’ve seen in the yard and patient enough to let me get some good photographs.


An adult goldenrod crab spider (probably female) waiting for pollinator prey

This is not the mother of the little spiders I found as after a female lays her eggs she stands guard over them, without eating, until she drops dead. As a cool piece of trivia, depending on the flower a goldenrod crab spider is waiting in ambush on, they can change colour between white and yellow, albeit much slower than a chameleon changes colour as the yellow pigments have to be fabricated taking 10 to 25 days.

Pretty and useful


My happy soapwort started from seed last year.

I don’t grow a lot of flowers just because they are pretty – I like them to have a secondary role like drawing in pollinators or feeding my resident hummingbird. Cosmos, sweet peas and nasturtiums I grow out of nostalgia as my parents grew them when I was a kid.

Last year, when I was pondering what to start from seed, soapwort intrigued me. I had no idea what the flower looked like, but the idea that a soap could be made from a plant hooked me. I’ve made soap in the past, but it’s a bit of a chore that I can’t be bothered with right now. Soapwort contains the same cleaning compounds as soap and sounds much quicker to make in a zombie apocalypse when I can’t get to the store. Apparently, one can even make shampoo from this plant.

This spring my soapwort bloomed and I was surprised at how pretty it is and it has been blooming constantly for a month. Even though it isn’t edible, this perennial is going into my embryonic food forest. Apparently it tolerates a bit of shade and neglect and becomes a nice ground cover (with a slight risk of taking over).


Soapwort flower close-up


my imperfect world


Kale flowers in the morning sun

We were ready to go a few minutes early this morning. My toddler’s sleep has really stabilized lately, allowing me to get the sleep I need – my whole world is better when I don’t feel like I’m dragging myself about in a sleep deprived haze. With the extra time, we went outside to see the chickens. The sun was just hitting the yard giving each leaf a rim of gold. The new growth looked almost magical in the light.

I still have a few beds full of last year’s plantings. I wasn’t fast enough harvesting kale buds so now my kale is now offering up their yellow flowers to the sun. I’ve been taking my time pulling up the plants because the flowers are so cheerful and I hope, by providing early food for the bees, the yard will get marked on their foraging maps. My broad beans are just starting to set out their pods – mostly they have won their winter race to grow faster than the slugs could eat them (my early peas lost that race).

In the golden early morning sun, my daughter and I stood by the purple sprouting broccoli munching on the crisp buds – a moment that felt perfect. Looking I saw the crumpled remnants one of my favourite red and yellow tulips in her other hand and remembered I prefer my imperfect world.


My pretty tulips – one of the few plants I grow just because they are pretty (I can see them while working in my office)


some brassica appreciation

My spring bulbs have burst into bloom – grape hyacinths, daffodils and snow drops are all showing off their colours. And the unseasonably warm weather has coaxed the plum tree behind the back fence to bloom (which isn’t necessarily a good thing as I haven’t seen a single bee). As pretty as the flowers are this time of year I really appreciate the brassicas for both being pretty (in a more subdued way) and their tastiness. So here are some cabbage-family pictures.


A volunteer kale that looks nothing like the kale I originally planted.


Purple sprouting broccoli which I should harvest soon


A kale sporting one of my favourite colour combinations of purple and green


Morning dew on my last January King Cabbage – I had to zoom in as this cabbage is roughly the size of a golf ball.


Tatsoi in a cold-frame – which clearly I’ve neglected as it has gone to flower. The little yellow flowers are lovely though.


Backyard Jewels


A golden buprestid – pretty enough to be a jewel

Nature’s best visual trick is iridescence, which can transform an ordinary beetle into something extraordinary. The dried up beetle carcass above is one of the prettiest examples of iridescence I’ve ever seen up close. The beetle is a golden buprestid (Buprestis aurulenta) which lives in my biome. As larvae they spend two to four years mining through recently dead conifer trees, whether that tree is rotting on a forest floor or part of your new coffee table, earning themselves the title of ‘pest’.

Once they morph beyond the furniture-eating stage, their exoskeleton matures to an iridescent green with brass coloured fringes around the wings. Strung together, these beetles would make a necklace suitable for a fancy ball, and I’m not the first to consider an iridescent beetle fit for a resplendent occasion. Ellen Terry, perhaps the most famous actress in the Victorian era, wore a green dress decorated with iridescent beetle wings to play Lady MacBeth in 1888. The dress must have looked stunning under the stage lights.

Beetles don’t hold a monopoly on iridescence; in fact, a diverse group of animals have independently evolved with their own version of colours with variable intensity and hue depending on the angle they are viewed (1). Examples abound in my own yard from dragonflies, butterflies to hummingbirds and more.

Why be iridescent?

An obvious use of iridescence is to communicate. A flash of bright colour might scare a predator away or say “I’m poisonous, so don’t eat me”. Or an animal could produce a flashy show to attract a mate (these guys put on the best show, but unfortunately don’t live in my yard). An untested hypothesis is that iridescence may help a school of fish or a flock of birds organize themselves (1) – another form of communication. For example, the iridescent patch on a mallard duck‘s wing may be a cue to help them fly in the same direction.

Counterintuitively, iridescent colours can also be used to hide (1), which explains why little fish like herring and sardines are so shiny – when looked at from below, their shininess blends with the shininess of the ocean surface. Or an animal can use iridescence to pretend to be something else – what looks like a drop of dew on a leaf might actually be a green leaf beetle (golden buprestids are probably to big to do this).


A drop of water on a leaf – or something else?

Interestingly, some instances of iridescence evolved before the organisms bearing iridescent structures developed the ability to see (1). One theory as to why iridescence evolved is that the structures that can create iridescence also create strength – so perhaps the iridescence of the golden buprestid is a side-effect of building a strong exoskeleton. We know these exoskeletons last, as fossilized beetles as old as 49 million years have been found that are still iridescent (2).

Now, I’ll need to find about a thousand more golden buprestids to make a ballgown of my own.


Golden buprestids from the collection of the Royal British Columbia Muesum



(1) Doucet, M. and M.G. Meadows. 2009. Iridescence: a functional perspective.

(2) Parker, A.R, and McKenzie, D.R. 2003. The cause of 50 million-year-old colour. Proc. R. Soc. B. 270, S151S153. 

My brain has been full

Remember the Calvin and Hobbs cartoon where Calvin asks his teacher if he can go home because his brain is full? I feel just like that. For months, my focus has been on preparing for the candidacy exam part of my PhD. The oral exam loomed in front of me like an oversized camper on a narrow road. The other side felt impossibly far away. Then exam day came and went. I passed. That was about a week ago, a week I’ve taken off.

I had planned on reading the stack of un-read books that I’ve collected, I’ve started four and finished none (I tend to read multiple books at once). I thought I would write the interesting blog posts that have been cluttering my mind – nope, haven’t written anything. Mostly, I’ve puttered in the garden and reconnected with friends. My brain has been full.

So with nothing interesting to write about, here are some pictures of flowers in my garden:


Nemophila menziesii ‘baby blue eyes’ – I have a thing for blue flowers


Borage – I planted these four years ago and they have self seeded ever since.


A gift form my folks – I don’t know what this is.


Purple poppies – seeds came from my mother-in-law


The household little person has been out into the garden as well.