natural history

Ballistic Plants

/ Robinne Weiss / Leave a comment

2016-03-05 19.16.53 smI only just harvested the black beans before they all exploded in the garden. It was the hot sun Thursday and Friday that did it. Friday afternoon, when I realised how dry the beans were, I raced to pick as many as I could, and was able to bring in the last of them this morning, with only a few losses.

Though it can be a pain for harvesting, I love plants with explosive seeds. As much as the explosion and shower of seeds, I like the empty pod afterwards. The tension that caused the explosion is gone, and the empty pod twists into attractive little corkscrews.

We have a weed in the yard with seeds so explosive, my daughter and I have dubbed it the seed-in-your-eye plant. It’s real name is bitter cress (Cardamine hirsuta). It’s common in the flower beds around the house, and has a habit of detonating just as a hapless weeder grabs hold of it (hence the seeds in the eye).

My favourite explosive plant is touch-me-not. Where I grew up, touch-me-nots sprang up in any moist hollow. As soon as they started flowering in summer, I’d start searching for ripe seed pods. I’d give each seed pod a gentle squeeze—if the pod was ready, it would burst under my fingers, sending yellow seeds scattering, and turning into a curly work of art. I loved the feel of the deforming fruit.

Sadly, my own children only have beans and bitter cress to detonate here. Now, if I can just convince them that shelling dry beans by detonating them is great fun…

 

Jewels in the Garden

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groundbeetlesmDigging potatoes for dinner yesterday, I came across one of my favourite New Zealand insects—the metallic green ground beetle.

When I teach about this insect, I always tell the kids it’s magical because at first glance it appears to be just a large black beetle. A closer look, however, reveals shimmering green around the edges.

Some individuals are more spectacularly green than others, and the one I found yesterday was one of the most vibrant I’ve seen.

Metallic green ground beetles are welcome in the garden. As larvae and as adults they eat slugs, grass grubs, and caterpillars—some of my worst pests.

But I think that what makes metallic green ground beetles most special is that they are endemic, not just to New Zealand, but to the Canterbury region. That means they are found nowhere else on Earth but in this little region of New Zealand.

They aren’t rare or endangered—they thrive in nearly every environment. They have close relatives nearby. But I appreciate the fact they are our own unique jewels.

Outside In

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2016-01-01 16.46.05Window screens are uncommon in New Zealand.

It’s not that there is no need for them. This time of year I struggle to keep the outside out of the house.

Flies, bees, wasps, mosquitoes, and moths all find their way in, to buzz, bite, and generally be a nuisance. Leaves and seeds blow in on the ever-present wind. And the occasional escaped chicken or feral cat wanders in, too.

So why no screens?

It makes sense if we look at why window screens are found elsewhere in the world.

In the United States, window screens were uncommon until the early 1900s, when they were suddenly mandated by local governments all over the country. An important advance of science was the reason for the new laws.

Today, with think of malaria, yellow fever, dengue, and a host of mosquito-borne diseases as tropical. But these “tropical” diseases, especially malaria, used to range all through Europe and North America. The ancient Romans invading Scotland, lost half their soldiers to Scotland’s local strain of malaria. Yellow fever and malaria were common in Boston and London. Philadelphia was decimated in 1793 by a yellow fever epidemic.

The connection between mosquitoes and malaria was discovered by entomologist Ronald Ross in 1897, and by 1900, mosquito control efforts were underway all over the world. Within a few years, window screens were being mandated by law in disease-hit areas. Most of those laws are still in place, as there is nothing preventing those mosquito-borne diseases from returning.

Here in New Zealand, we are remarkably free of mosquito borne diseases. Malaria, and yellow fever have never gained a foothold, though they almost certainly have shown up now and again in the form of sick travellers.

With no mosquito borne disease, the biters that slip in through my windows every night are just a nuisance, so screens haven’t been written into the building code.

But they would be nice to have…

Thrips

/ Robinne Weiss / 1 Comment

2016-02-12 10.51.28I can’t help but think about thrips at this time of year. They seem to love my office. They crawl everywhere. I’m constantly swiping them off my face and arms, and they end up in drifts on my desk when they die.

Thrips are tiny cigar-shaped insects with hairy wings (the order name, Thysanoptera, means fringe-winged). Most suck plant juices, and they leave characteristic little puncture wounds in leaves. Some transmit plant diseases.

Thrips are fascinating insects for a number of reasons.

Their development from egg to adult is not quite incomplete metamorphosis (in which the young look like the adults, but lack wings), and is not quite complete metamorphosis (in which the young look very different, and go through a pupal stage before adulthood). It’s a mix of both, and differs among species within the order.

Thrips are also left handed. As a south paw myself, I appreciate this. Instead of having a symmetrical mouth, like most other insects, with mandibles on both sides, thrips only have a left mandible. No one knows why this is the case. I like to think it’s because left handedness is just better.

Another thing I find intriguing about thrips is that some species will bite people, though they feed on plant juices. Our thrips, which I believe are Limothrips cerealum, the grain thrips, have this annoying tendency. They don’t bite often, but now and again you’ll feel a little stab and wonder what the insect is playing at.

Even linguistically, thrips are interesting. “Thrips” is both singular and plural—one thrips, many thrips. Thus, in the following poem, I couldn’t rhyme thrip with trip, it had to be thrips with sips…;)

 

Thysanopteran

Little thrips,

What does it think

As it delicately sips

The juices of plants?

 

Does it prefer

My prizewinning rose?

Or does the pollen

Tickle its nose?

 

Does it find

The broccoli sweeter?

And how can it be

Such a big eater?

 

 

Mullein

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2016-02-07 10.22.37Today we discovered a new weed in our yard—that brings the total tally of weed species on the property to 57. The new plant is mullein (Verbascum thapsus), a native to Europe, and a common weed all over the world. Our specimen was young–just a tiny floret, but during its second year, mullein can send up a flower stalk almost 2 metres tall.

Like many garden weeds, mullein was almost certainly brought to New Zealand on purpose in the early 1800s. It seems to have been used for nearly everything by various peoples at various times in history.

The Romans used the flower stalk dipped in tallow as a torch.

It has been used since ancient times as a remedy for coughs and asthma (in people and livestock), either by drinking a tea made of leaves or flowers, or by smoking the leaves.

It either ensured conception or prevented it, depending upon what place and time you lived.

It’s fuzzy leaves, rubbed on the cheeks, impart a rosy hue, like rouge. Preparations made from the leaves can also soften the skin.

A yellow hair dye can be made from the flowers.

A green dye can be made from the leaves (probably best not to use this on your hair—it’s apparently permanent).

It was supposedly used by witches and warlocks, and was considered a charm against demons.

Its fuzzy leaves can be used as a thermal lining in your shoes.

And, of course, as any Boy Scout knows, it makes fine toilet paper!

Just remember to keep track of which leaves you’ve used as toilet paper, so you don’t use them for tea…;)

Damselflies

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2016-01-31 13.44.27 cropTwo years ago, my husband did what he’d been threatening to do for years—he dug a pond. At some point, I’ll write a blog post on the pond itself, but today I want to talk about the damselflies that live there.

I took a break from my work this morning and spent a few minutes sitting beside the pond. It was swarming with red damselflies (Xanthocnemis zealandica). They were mostly males jockeying for the best territories—chasing and dive bombing each other, all short jabs of snapping wings.

2016-01-31 13.44.40 cropThe females were there, too. Every one I saw was being guarded by a male as she flitted from plant to plant, dipping her abdomen into the water to lay her eggs in the plant’s submerged stem. Damselfly mate guarding is awkward at best—the male grasps the female behind the head with claspers on the end of his abdomen and discourages other males from mating with “his” female. Both insects must beat their wings to keep the pair aloft, and as I watched them, it wasn’t at all clear to me who chooses the spots to stop and lay eggs.

When a pair stops, the male often supports himself entirely with his claspers, tucking in wings and legs and forming a bizarre appendage to the female as she gets down to business. She appears completely oblivious of her escort, resting after laying each egg, as if to say, “If you want to cling there in that ridiculous pose, that’s fine by me, but you’re not going to rush me.”

The eggs these girls lay will hatch in a week or two, and the nymphs will spend nearly a year living in the pond, eating other aquatic invertebrates with a hinged, extrusible mouth that is the stuff of horror movies, before emerging from the water as adults.

I sat and watched the spectacle for a while, and just as I was about to leave, I was treated to the sight of the other damselfly resident in this part of New Zealand—the blue damselfly (Austrolestes colensonis)—a large neon-blue insect that makes the red damselfly look dull.

Unfortunately, he didn’t stick around for a photograph, but I’ll be looking for his nymphs in the water later in the year.

Hedgehogs

/ Robinne Weiss / 7 Comments

2016-01-26 18.07.41 smThey’re adorable and unafraid of humans. They eat snails, slugs and grass grubs. What’s not to like about hedgehogs?

Unfortunately, a fair bit, here in New Zealand. In addition to eating pests, they also feast on ground nesting bird eggs and chicks, skinks, and many native and endangered invertebrates.

And they’re more common in New Zealand than they are anywhere in their native habitat.

And I think they’re more common in our yard than anywhere else in New Zealand.

Now that the days are getting shorter, I regularly step on them in the dark when I’m out milking and feeding the animals. I certainly wouldn’t walk barefoot through the yard at night here.

They snuffle around the flower beds, snorting and grunting, oblivious to anything non-edible. They spread compost all over the yard.

They also apparently love cucumbers—last year I had to trap one out of the garden after it managed to squeeze in through a hole in the rabbit fencing. It took a bite out of each cucumber—obviously trying to find the perfect one.

They like the apples and peanut butter I bait the possum traps with, and though I don’t aim to kill them, I will admit that I’m not upset when I catch a hedgehog instead of a possum (my trapping seems to have no effect whatsoever on the population of either pest, anyway…). They snatch the eggs of the spur-winged plovers that nest unsuccessfully every year in our paddock, and I’d much prefer plover chicks to hedgehogs in the yard.

It still doesn’t stop me from smiling when I see one trundling along through the grass.

They are adorable after all…

Solanaceae

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Tomatillo

Tomatillo

Solanaceae—one of my favourite families of plants.

There are more than a few members of this family in the vegetable garden:

Tomatoes, potatoes, eggplants, cape gooseberries, capsicum (peppers), and tomatillos are all solanaceous plants.

Nicotiana

Nicotiana

But they don’t end there. In the flower garden there are petunias and nicotiana, among the perennial fruits are gogi berries, and in the native garden there is poro poro.

And, of course, growing as weeds everywhere are black and hairy nightshade (these don’t get my favourite plant vote).

This diverse and sometimes tasty group of plants also includes many containing medicinal, poisonous or psychoactive chemicals (tobacco, mandrake, and deadly nightshade among them). Indeed, it’s best to be careful with the Solanaceae—even the edible ones contain poisons in the non-edible portions of the plants, or, as in the case of green potatoes, even in the edible parts. Solanine is the culprit in green potatoes—it causes diarrhoea, vomiting and hallucinations, and its bitter taste prevents herbivores from eating the potatoes. Other chemicals in the Solanaceae can have the opposite effect—reducing nausea in chemotherapy patients, and reversing the effects of poisoning by certain pesticides and chemical warfare agents.

And we’re still discovering more uses for these pharmacologically rich plants.

What’s not to like?

To Bee or Not To Bee

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2016-01-14 17.14.44 cropStock photos are terrible things. Not just because they’re often lousy, vapid images, but because they lead to errors of identification. If I had a dollar for every insect misidentified in a stock photo, I’d be a rich woman.

Take this lovely insect (not a stock photo, by the way, but one of my own). Sipping nectar from flowers, black and yellow stripes, must be a bee, right?

Wrong.

Look more closely.

Bees have four wings, flies have two.

Bees have generously sized, usually elbowed antennae. Flies either have long, filamentous antennae, or short bristle-like antennae.

Bees’ eyes never cover their entire head. Flies’ eyes often do.

Bees are usually quite furry. Flies are often hairless.

Yes, this is not a bee, but a fly. This is a narcissus bulb fly—a type of syrphid or flower fly. It is an excellent honeybee mimic. Not only does it look like a bee, but it acts like one, too, down to the pulsing abdomen and the hanging pollen baskets in flight.

The disguise keeps the fly safe—potential predators assume it is a honey bee and leave it alone. Of course, it lacks the sting of a honeybee, so it would make a tasty snack for any predator who can identify it.

Fortunately for the fly, most predators, like most people, won’t give it a second look, and will steer clear of it.

Which gives rise to one of my favourite “party tricks”—grabbing the “bee” in my bare hand, and then releasing it, neither of us harmed.

But of course, now that won’t work on you…

Now you know…

To bee or not to bee?