into the season of spiders

I blame these guys for continuously having to wipe webs off my face the last few days

We are currently suffering though a late summer heatwave. If I hadn’t recently melted my thermometer in a tempeh disaster (I kinda forgot the tempeh was incubating in the oven, along with plastic thermometer, when I turned it on to make pizza), I’d give an exact temperature. My guess is that my house is ten billion degrees as a result my brain is melting.

On that note, and considering around here we are in the season of spiders, meaning I can’t walk through by back yard without walking through dozens of spider webs, I thought I’d resurrect a post from when I started blogging


I’ve been reading Rachel Carson‘s ‘The Sea Around Us’ after discovering it among my books during my recent move. My grandfather gave it to me when I first expressed interest in ocean science many years ago. The book was presented to him in the 1950’s in recognition of meteorological measurements he took as a mariner. When I first was given the book I started reading it, but didn’t finish so when I found it this time I thought it was time to sit down and read the whole book.

In her chapter on island formation, this intrigued me:

So bare and desolate that not even a lichen grows on them, St Paul’s Rocks would seem one of the most unpromising places in the world to look for a spider, spinning its web in arachnidan hope of snaring passing insects. Yet Darwin found spiders when he visited the Rocks in 1833, and forty years later the naturalists of H.M.S. Challenger also reported them, busy at their web-spinning.

Spiders? How did they get there? St Paul’s Rocks are near the equator right in the middle of the Atlantic Ocean. Discovered by the Portuguese navy in 1511 by accident, that is by crashing into them, these islands are now part of Brazil. They jut up from the ocean floor 800 km off the coast of South America, and are made up of 15 small islands and rocks with a highest point of 17 m. This group of islands is one of the few places (Iceland is another) where the mid-ocean ridge breaks the surface. Currently, the Brazilian Navy has a science station and a lighthouse on the islands.

On the 16th of February, 1832 the H.M.S. Beagle stopped at St Paul’s Rocks and Darwin had an opportunity to explore. His inventory of life included: 2 types of sea birds (boobies and noddies), a type of large crab, a fly, a parasitic tick (preying on the birds), a moth that survived by eating feathers, a beetle, a woodlouse and lots of spiders. He also observed that not a single plant or lichen could be found, since that time mosses and grasses have found their way to the island, probably helped by people.

Not including the crab, the only life form on the island that can’t fly or hitch a ride is the spider. No spider can fly, even though there is an Australian spider called the flying spider. Flying spiders are tiny with pretty blue and green iridescent colouring. Their abdomens have flaps that can be extended allowing them to glide when they leap, increasing their range. But even an ability to glide wouldn’t help spiders colonize remote islands.

Young spiders are forced to move away from their parents and siblings to avoid competing for food and other resources with them. To begin their journey, a spider climbs to a high point, and then point its abdomen into the air. It releases a long filament of silk that is picked up by the wind, taking the little spider up into the sky. Drifting spiders have been found thousands of meters above the remote Hawaiian Islands. Or according to Rachel Carson:

Airmen have passed through great numbers of the white, silken filaments of spiders’ ‘parachutes’ at heights of two to three miles.

Drifting is a great way to travel as it requires no energy expenditure from the spider. I wonder how many of these drifting spiders eventually find a suitable home?

Arachnophobes beware!

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A garden spider (Araneus diadematus), one of the most common web-spinning spiders in my area, originally introduced from Europe. This one had set up shop in my backyard.

In the spirit of the season, it’s time for some creepy crawlies…

So far we’ve identified more than 10 species of spiders living in the garden and no doubt there are many more types. I love seeing spiders in the garden because they eat the animals that are eating my food. In one English study, in late summer one hectare of meadow was found to contain roughly 5 million spiders which suggests these predators are consuming way more harmful bugs than birds do (ref).

All spiders are venomous – venomous means that if that animal bites or stings you a toxin will be put in your system while a poisonous animal will make you sick if you eat it. As far as I know you could eat a spider if you wanted to (I base my spider edibility knowledge off of seeing people eating roasted tarantulas in a move once instead of actual fact). Most spiders are incapable of biting through human skin, especially around here. There are some exceptions, black widow spiders for example but I’ve never seen one in real life.

Spiders fall into two general categories – those who spin webs to catch their prey and those who don’t opting for ambush or stalking techniques instead. I have to admit that I absolutely despise walking into spider’s webs – when I roamed the forest as a kid I would always wave a stick in front of my face where ever I went to prevent accidentally getting web on my face. Now I try to avoid wrecking spider’s webs, leaving the spiders to catch their dinner in peace – mostly. Occasionally, when my daughter asks, I’ll ’tickle’ a web so the spider rushes out to investigate.

Beyond being protectors of my food, spiders are amazingly diverse and often quite beautiful. So to any arachnophobes out there, who’ve made it this far into my post – take a look at these links and check out how fantastic spiders can be (go on I dare you):

Here are 10 beauties.

This one is my favorite.

And here is a roundup of local ones.

And, for any arachnophobes still with me, I thought I should mention some spiders have figured out how to soar in the sky. They can’t fly, but using a strand of their silk like a kite they can drift with the wind. More here.

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Another garden spider – but this one had an abdomen roughly the size of my finger nail.

Happy Halloween!

wildlife in the food forest

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The visiting Cooper’s hawk – check out his jewelry.

Converting the monoculture of my front lawn into a more diverse ecosystem was one of my goals when we started building a food forest last year. For wildlife we took a ‘build it and they will come’ philosophy that has worked. Bees and ladybugs quickly moved in as soon as there were flowers, and spiders have spun their webs everywhere. Little birds now hunt for food among the trees and plants – juncos, golden crown sparrows, and fox sparrows find meals on the ground while the Anna’s hummingbird that calls our yard home frequents the flowers, especially the currently blooming broccoli.

A couple of days ago I spotted something new – a Cooper’s hawk was perched on the top bar of our not-deer-proof fortification intently watching the old laurel bush by our deck. The laurel bush is covered with berries I suspect are toxic but the neighbourhood robins had taken to feasting on them (based on the droppings on the deck, the berries appear to disagreeing with the robins digestive systems). Hundreds of robins were flocking to the bush and capturing the hawk’s attention. Cooper’s hawks regularly eat robins and this one had figured out a trick.

Every now and then some robins would spook and fly off. The dumb ones flew low into the fortification netting. Bird panic ensued as they discovered their path was blocked, as the robins frantically looked for a way out the hawk would swoop in. I didn’t see him catch his dinner, but I’m sure in time his method would be successful.

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My visiting hawk is the one on the far left (photo by Andy Stewart)

I took a couple pictures of the small raptor since he was distracted enough to let me get close. When I showed the pictures to my husband we noticed the bird was banded and we could clearly make out the number on his band. My husband used his contacts to find out a little about the bird and to report that we saw him. It turns out this hawk was born in town sometime in the spring of 2010 and banded shortly thereafter – I was even sent a baby picture. He looks like a healthy urban hawk to me and I’d be happy to see him again in the yard.

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A representation of deer congregating to eat my food – I don’t have any actual pictures because when I see them I’m busy chasing them away.

Other, more problematic wildlife I wish wouldn’t visit. My food forest has been slow to develop mostly due to wily deer that keep finding ways inside our not-deer-proof fortification. Since I irrigated all summer, inside the fortification was lush and green compared to the parched lawns on the outside. Clearly, I created a tasty destination for our urban deer. We’ll be rebuilding the fence over winter to prevent (hopefully) the problem next summer. The pole beans and broccoli took the brunt of the deer damage, but my apple and cherry tree were also munched on – hopefully they recover next spring! As an aside both the ground cherries and Irish poet tassel flowers were entirely ignored.

Revenge on the Wasps

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One of the villains hanging out in the cilantro

“It’s a trap!” – Admiral Ackbar from Return of the Jedi

Sadly, summer is clearly winding down, days are noticeably shorter and dew has returned in the morning. Our calorie dense winter crops are starting to mature (more on that later). Spider webs appear over night across seemingly impossible divides and I despise walking into spider webs. I suspect all the spiders will migrate inside the house for the winter – the spider equivalent of heading to Florida. I don’t mind spiders inside the house as long as I don’t see them – the ones I see get evicted. Wasps are a different story.

The wasps started getting desperate for food early this year swarming around the yard and house looking for grub. They rely heavily on smell to find food, their noses leading them directly into the kitchen (unfortunately, we don’t have screens). Regularly, we were swatting one or two yellow-and-black banded bandits. Their bold colouring a warning of their sting. Unlike a bee, a wasp can sting more than once and they don’t hesitate to do so (a bee’s stinger gets ripped out when it stings, which is fatal to the bee). Plenty of animals eat wasps like other wasps, spiders, dragonflies, beetles, moths, crabs, badgers, frogs, fish, birds, skunks, bats, rats, mice, etc. So wasps do fill a ecosystem niche – but I have limits to my tolerance of them.

While making applesauce with my little helper, I counted twelve wasps buzzing around her head – that was the last straw. I hate the idea of poisoning my yard or home, so we settled on using a wasp trap. Within a day we caught dozens (I’m stunned there were that many around). Now the trap is so packed, wasps have to force their way in – and we are still catching them.

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The trap after about a day

As a tangent – people also eat wasps, or more specifically, wasp larvae. I’ve read (as I’ve never met anyone who eats insects) the larvae taste great fried in butter, further support to my theory that butter can make anything taste good.

Things to do with chives plus a surprise

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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.

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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:

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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.

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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.

purple puff-balls and their pollinators

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purple puff-balls on the move

The chives are almost done their spring-time race to re-seed themselves – part of what I suspect is a cunning chive-y plan to take over my entire garden. Innocent-looking purple puff-ball tops are threatening to over run the strawberries and basil I planted either side of them.

I have more chives than I could ever expect to use – but that’s okay because the pollinators love their flowers. As I approach the chive domain I can hear the buzz of insects collecting their lunch. A traffic jam of honey bees, bumble bees and mason bees visit flower after flower. Other insects with odd shapes (that are probably bee flies) add even more diversity. One category of visitor is so small and fast I can’t really tell what they look like.

More than once by daughter (two and a half) has followed the buzzy cacophony to the chives. She is fascinated by them. If I look away for a moment, she’ll climb among the chives to get a good look. I love that her curiosity drives her to discover more about the world going on right under our noses – reason enough to spend time in the garden.

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A honey bee collecting pollen (they are hard to take pictures of because they never sit still)

I tell her that the pollinators have important work to do and that she is to look and not touch them (so far she hasn’t been stung). I point out the names of the ones I know – no doubt in a few years she’ll be telling me the names of the rest.

Introducing the chicken-coop fly

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I’ve decided to call these insects chicken-coop flies as their universe seems to be centered on the coop

While digging up photos for my golden buprestid beetle post from yesterday, I found a couple other great examples of iridescence from the yard. The metallic fly above and dragonfly below. Eons ago when I started this blog I wrote about how iridescent colours are formed – here is part 1 and part 2 of my explanation.

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Another shiny garden visitor

 

Backyard Jewels

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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).

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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.

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Golden buprestids from the collection of the Royal British Columbia Muesum

 

References

(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. 

A trio of unrelated topics

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A different funky ladybug -a Multicoloured Asian Lady Beetle

I don’t have a complete blog post in my head, so here are three unrelated topics I’ve been thinking about.

1. Last week, during our first cold snap of the year, I found another unique lady bug active in the garden (first one here). This one was much blacker that others I’ve seen. It turns out its a Multicoloured Asian Lady Beetle (Harmonia axyridis), first introduced to North America in 1916 to control aphids and is now well established.

2. Here, the rainy season is well underway. I actually don’t mind the rain, but then, I grew up in this environment. I recently read an interesting article (check it out here) about the scent of rain. Like instruments in an orchestra, the smell of rain originates from microorganisms emitting organic compounds as perhaps a collective call for help, plus notes from plant oils and fungus. One of the culprits is the compound geosmin, whose name literally means ‘smell of the earth’. Geosmin was isolated and identified in 1965 – yet I don’t think it is in any of the commercial grooming products (like deodorant) that claims a rain scent as they never actually smell like rain.

3. The colours in nature never cease to amaze me, which is why I’m currently reading ‘Colour: Travels Through the Paintbox’ by Victoria Finlay for a second time (I’m on the chapter about red dyes from insects). Blue in nature is a particularly interesting colour as natural blue pigments are rare. When I first started this blog, I wrote about blues here, here, here, here and here (clearly this is a favorite topic of mine). I recently stumbled upon this article which is a great explanation of the topic.

should I eat bugs?

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Exotic grasshoppers are not on the menu at my house

While we were browsing in a Beijing market, my traveling companion spotted BBQ scorpion on a stick for sale (I know scorpions aren’t insects, but for food stuff they fit in the ‘insect’ category in my mind). Each stick held five scorpions glistening with sauce. The possibility of a novel experience took hold and she begged me to try scorpion with her – I didn’t*. Although that trip was years ago, recently, everywhere I look someone is writing about eating bugs (there is a lovely account of someone who plunged into bug eating here).

There are plenty of good reasons to substitute some of ones protein needs with buggy-goodness – many of which are outlined here. You can raise an insect based protein source in a small amount of space, perfect for an urban gardener like me. I have no problem producing enough leafy greens for my family and to give away, but I’m short on protein sources. Leaving me to wonder if I should revisit my decision to not eat bugs.

In the past for pet food, we’ve raised mealworms in the house. Mealworms are non offensive insects who happily live in an aquarium with a thick layer of bran. Their adult form is a flightless beetle – so they don’t escape. They’re dry, so no smell. They are also edible – I could easily throw a handful of meal worms into my morning smoothie, then blend them in – but I won’t.

Even though I intellectually agree with all the pros for eating bugs, I’m not yet ready to do it. I grew up in a culture where bugs are not considered food and even though I’m willing to eat all sorts of things, the thought of bugs as food still grosses me out. Perhaps some day I’ll work up the nerve to try eating insects or perhaps not.

How about you?

*Without me, my traveling companion went ahead and bought herself a stick of scorpions. On her first bite, scorpion-juice splattered down the front of my shirt – I never got the stains out of that shirt.