Spring Babies

It’s that time of year again! The preying mantis egg case I collected in the autumn is hatching.

Because these mantids were in the warm office for half the winter, they’re early. Mantids in the egg cases outdoors haven’t yet emerged. So they need a little extra care. As the babies emerge, I transfer them to a large tank where they’ll be warm and well-fed for a few weeks while the weather improves. Eventually, I will release most, keeping only a few for use in educational programmes.

I never tire of this annual event. I love watching the newborn mantids stretch their legs and catch their first meal. And I’m always amazed that so many insects can emerge from such a small egg case. The current one, just 15 mm long, has disgorged 35 mantids so far, and only half the case has hatched. The mantids don’t all hatch at once—hatching seems to progress from one end of the egg case to the other over the course of a few days. In the wild, I suspect most of the later hatchlings are eaten by the early ones—it’s a mantid-eat-mantid world out there. It happens in my tanks, too, though I try to minimise cannibalism by spreading them out as much as possible and giving them plenty of hiding spots. I used to raise each individual in its own peanut butter jar, but that gets to be pretty time and space-consuming when there can be 70 mantids in each egg case.

Everyone’s heard the sensational ‘fact’ that female preying mantids eat the males after mating. It does happen, sometimes, in some species, but not as often as you might think. Mantids are creatures of instinct, and one of their most powerful instincts is to capture prey. In fact, this urge is so strong that, even when their digestive system is completely full, and they can’t actually eat anything else, they will continue to capture prey.

So it’s no surprise that a female mantid might snack on her mate, especially since she’s bigger than he is. In species where the females are significantly larger than the males, there’s a higher incidence of cannibalism after mating. Among New Zealand mantids, cannibalism at mating is rare—females are only slightly larger than males, and so the males have a good chance of fighting off the females. I’ve seen this in action in captivity—one of my females had a go at her mate, but he was every bit as feisty as she, and their tussle ended with both alive and unharmed.

My little babies won’t have to worry about mating cannibalism for a while yet, but there are plenty of other dangers out there—other predators, parasites, pathogenic fungi, freezing weather, and careless gardeners all take their toll. Of the maybe 70 mantids that will hatch from my egg case, only one or two are likely to survive to adulthood.

I’ll give my babies the best start I can, and then they’ll be on their own. Watching them now, catching gnats like pros, I think they’re well-equipped.

5 Simple Things You Can Do to Help Conserve Species

It’s Conservation Week here in New Zealand. Fittingly, one of the kōwhai trees we planted years ago has chosen this week to flower for the first time.

Conservation week is a good time to talk about backyard biodiversity. I’ve blogged more than once about biodiversity issues. It’s a topic near to my family’s heart, and something we strive to improve all the time.

Our yard is, unfortunately, home to a wide variety of non-native weeds, but it also sports native plantings (and even a fair number of native ‘weeds’). Here are just a few of the simple things we’ve done to improve the habitat value of our back yard for native organisms. You could do these, too.

  1. Plant natives instead of non-natives. Here in New Zealand this is especially important, but it’s a good rule of thumb wherever you live. Native vegetation will best support native wildlife, because they evolved together. Choose plants that provide food and shelter for local wildlife—shrubs with berries for birds and lizards to eat, dense grasses that provide hiding spots for invertebrates, and flowers that provide food for insects.
  2. Create lizard refuges. A pile of rocks or a stack of broken terracotta pot shards makes a nice refuge for lizards—the rocks and terracotta warm up in the sun, making a convenient basking spot for the lizards, and the little cracks between ensure a quick, safe get-away when predators appear.
  3. Just add water. Birds, insects, and other animals all need water to survive. Provide a bird bath, a small pond, or an attractive water feature, and you’ll find many more animals drawn to your yard.
  4. Kill non-native predators. Less important in some places, but here in New Zealand, protecting native birds and lizards requires controlling invasive predators. Trap out possums, stoats, and rats to give native birds a chance to nest successfully. Put a bell on your cat and keep it indoors around dusk and dawn when the birds are most vulnerable.
  5. Learn what you’ve got. No matter how small, your yard teems with species. Look closely, and you may be surprised at the diversity. Though our yard tends to be quite dry, we’ve discovered half a dozen species of moisture-loving slime moulds on the property. Once you know you an organism is present, you can tweak your planting and maintenance to protect and encourage it.

And that brings me back to the kōwhai tree, finally blooming. It’s not enough, yet, to attract bellbirds or tūī, across the vast stretches of agricultural land between us and the nearest populations, but someday, our kōwhai and flaxes, along with the neighbours’, may very well support a healthy population of native birds. All it takes is for each of us to care for our own backyards, and collectively we can improve the habitat for all our native species.

Shining in the Dark

Not much to look at in the light, but spectacular in the dark.

I’m a morning person. I’m rarely in bed past six o’clock, and am often up long before that. But I will admit that even I get tired of getting up in the cold and dark at this time of year.

Of course, sometimes the most amazing things happen before the sun is up.

Yesterday morning, I stepped into the chicken paddock feed ‘the girls’. It was still dark, with just enough starlight to see my way. I bent to tip a scoop of feed into their dish and froze.

Something glowed on the ground—the eerie glow of bioluminescence.

I’ve seen bioluminescence while feeding the chickens before—a tiny sea creature whipped up and blown in with a violent snowstorm—but this was different.

I flicked my light on and saw something pink glistening on the ground. When I tried to pick it up, I discovered it was the head of an earthworm.

A brightly glowing earthworm.

I couldn’t get it out of the ground in order to bring it in and identify it yesterday, but I took the spading fork with me this morning when I went to feed the chickens, and I collected a little glowing earthworm from where I’d seen one yesterday.

I already knew that at least one of our native earthworms is bioluminescent—Octochaetus multiporus, which I’ve blogged about before. But O. multiporus grows to enormous size, and I’ve never found any worms in the garden that match its description. Doing a little research, I found that bioluminescence is quite widely employed by earthworms, presumably as a deterrent to predators.

Most earthworms produce light in much the same way that fireflies do, with a chemical known as luciferin that reacts with oxygen-containing compounds in the presence of luciferase to create light.

So, what species is my little glowing worm? There are about thirty New Zealand species within the genera where bioluminescence has been recorded. I’ve found record of only two of those species being bioluminescent: O. mulitporus and Microscolex phosphoreus, a small worm considered native here, but widely distributed around the globe. My best guess is that it’s M. phosphoreus, but data on that worm’s distribution in New Zealand is almost nonexistent (it’s been recorded from only one location), and data about any earthworm in New Zealand is scanty. Perhaps my worm is M. phosphoreus, but it might also be a worm in which bioluminescence hasn’t been recorded. After all, most people aren’t out in the garden at night to notice glowing worms.

Hopefully, I’ll be able to have the worm identified by an expert. If not, well, I still think it’s the coolest thing I’ve seen in a long while! And I won’t be grumbling about getting up in the dark and cold tomorrow.

Springtime in the Office

And so it begins…

It’s been nearly a week since my last blog post, but I have a good excuse—I’ve been working very hard, and have just finished the first draft of The Dragon Defence League, book 3 in my Dragon Slayer series.

Spring has crept into my office, though, in spite of my focus on writing. Over the weekend, I started my first seeds for the season: peppers, eggplants, herbs, brassicas, onions, lettuce and spinach. I’ve been writing in a greenhouse the past two days, with the smell of moist potting mix mixing with the smell of my morning coffee.

Next week I’ll add another batch of seeds to the office, and before long I’ll be hauling newly-sprouted seedlings out to the greenhouse. And not long after that, those seedlings will be ready to set out in the garden.

So much excitement in spring! And now a new book to nurture along with the plants!

Nifty Nematodes

Nematodes under the microscope. Image: CSIRO

A week or so ago, during a writing break, I spent some time peering through the microscope in my ongoing quest to find tardigrades in our yard. I had no luck on the tardigrades, but as usual I came across lots of fabulous little invertebrates.

Perhaps the most common creatures under the microscope were nematodes. No surprise, really. Nematodes are the most common multicellular organisms on earth; there are several million in every square metre of soil here in New Zealand. Most are tiny (less than 3 mm). But not all are so minuscule; the largest, a parasite of sperm whales, can grow to 8 to 9 metres in length.

Nematodes can be free-living or parasitic on animals and plants. In fact, most animals (vertebrate and invertebrate) and plants are host to at least one specialist nematode parasite. Free-living nematodes eat bacteria, fungi, or small invertebrates (including other nematodes).

As you can imagine, nematodes are of huge importance ecologically, economically, and from a human health perspective.

Humans are host to about 60 species of nematode. Diseases caused by nematode parasites in humans include: ascariasis (an intestinal infection that can cause growth retardation and a variety of intestinal and other problems), hookworm (causing anaemia and developmental problems),filariasis (a lymph infection, causing swelling in many body parts, including elephantiasis of the legs), trichinosis (an intestinal infection causing diarrhoea, fever, and other symptoms). Many nematode infections are asymptomatic, and it’s likely most of us play host to nematodes for most of our lives.

The control of nematodes is important in agricultural systems. Worldwide crop loss to nematodes is estimated to be 12.3 percent of production (US$157 billion). Livestock and domestic pets are also susceptible to nematode infection, and millions of dollars annually are spent to control nematode infections including lungworm, hookworm, trichinella, heartworm, and many others.

But nematodes aren’t just doom and gloom. They’re integral parts of natural ecosystems, and critical components in nutrient cycling (especially nitrogen) and food webs. They regulate the bacterial population in the soil, and provide food for many organisms (including some fungi, which catch nematodes with lassos, like tiny cowhands). They can be useful, too. Some insect parasitic species are bred to help control insect pests—a highly species-specific, organic control method.

And like the tardigrade, nematodes are tough. A culture of live nematodes aboard the Space Shuttle Columbia were the only organisms to survive the re-entry breakup of the shuttle, making them the only organism known to survive unprotected atmospheric descent.

Fabulous Flatworms

Australian flatworm

One of the common animals in my yard and garden is the flatworm. Strictly speaking, “the” flatworm here in New Zealand is actually multiple species—possibly up to a hundred—but they have been poorly studied, so it’s unclear just how many species there are.

Flatworms are some of the most impressive predators in the garden, able to consume prey up to 55 times their own size. That’s the equivalent of your house cat taking down a female elk. They eat snails, slugs, and earthworms, digesting them externally before sucking them up with one or more mouths located midway along their bodies.

I love to find flatworms around the yard. They come in striking colours, and some have lovely brown stripes—the orange Australian flatworm (Australoplana sanguinea) is most common in my garden, followed by the relatively nondescript brown New Zealand flatworm (Arthurdendyus triangulatus). Like the slugs they eat, they prefer damp places, and they protect themselves with a layer of mucous. Flatworm mucus is stickier than slug mucous, and they use it to attach themselves to their prey during feeding.

New Zealand is full of non-native invasive organisms, but New Zealand flatworms are one of the few organisms that have turned the tables and become pests overseas. They are easily transported in potted plants, and have successfully invaded Ireland and Scotland. Though there was widespread panic at first about their potential to threaten the local ecology, they appear to have caused little damage to earthworm populations in the UK. Like most cold-blooded animals, their appetites are small. Far from being a devouring hoard, each flatworm can manage, on average, just one earthworm per week. And if they don’t manage to find an earthworm every week, it’s not a problem—they can go a year without eating.

Weeding Therapy

You know it’s been a good therapy session when it leaves a clear weeding front.

I make no secret of the fact I have a weeding problem. I’ll ignore hunger, thirst and bodily pain to pull just a few more weeds—fill the wheelbarrow, finish the garden bed, never mind the cost.

But in spite of my obsession, I believe there is a place for weeding therapy, even for me.

Today, when the temperature hit a sweltering (for mid-winter, at least) 18 degrees (64ºF), I had no interest in my usual lunchtime walk. No. Today, after weeks of inactivity in the garden, I needed to weed.

I grabbed my gloves, and hove to. A sweaty half-hour later, I was refreshed and ready to get back to work.

The key to good weeding therapy (to avoid it becoming a weeding marathon) is setting limits—I give myself half an hour, and set a timer so I’ve no excuse for running over time. It helps to choose the therapy weeding job well; I go for places that have been irritating me, places that are desperate, or places where the weeds are big and easy to pull. It gives me a greater sense of accomplishment in a short amount of time, so I feel I can quit when my time is up.

And if I do quit before exhaustion, pain or hunger set in, I can return to other work in a focused state of mind, ready to bang out the next chapter or tackle the next editing job.

And the best part is that, with so much garden area here, there will always be more weeds, so therapy is always available when I need it.