7 Habits of Highly Successful Invaders


I was driving home from work, appreciating that the switch has been flipped, and suddenly! Spring. The greens are moving all misty into view, and predominantly among them here in Southern Ohio is the Amur Honeysuckle. I was contemplating this, and how that trait is one of the things that makes it a highly successful invasive species, and it dawned on me that there are more ways to invade than are portrayed in movies about aliens. Sure, overwhelming military force is one way. But what other things have species done here on Earth that enabled them to conquer and victoriously rule the forest field stream continent?

  1. Get there early, stay late.

This is what the Amur Honeysuckle, among many other weed species, does best. It’s among the first underbrush growth to develop leaves in the spring, and it holds onto those leaves well into winter for other species. This means it usually shades out any competition, like the local plants that used to hold these undergrowth niches, including raspberries and blackberries (in my area). Also, it’s got a ton of tasty berries that draw in the birds, who then help spread the nuisance wherever they poop.

  1.  Breed Early and Often.

The cuckoo, renowned the world over for their abilities to persuade other species to raise their offspring while they are off cavorting, doing the nasty, and then laying yet more eggs in innocent nests, ensure their prey not only has to raise the chicks, but that their cuckolded targets lose their own chicks due to the quick hatch rate of the cuckoo. The cuckoo chick, hatched out, shoves the other eggs, or even smaller chicks, out to make room for itself to receive all the attention.

  1. Forced abortion and rape.

This particularly abhorrent technique is the purview of the cold-blooded Rusty Crawfish, which takes over streams all across the US of A by main force. Native to the Ohio river, males of this species will mate with any females, regardless of species, and will rip out the spermatophores left by males who came before them to ensure their own biological dominance.

  1. Spread Disease

This is not a sustainable method for the long term, but Emerald Ash Borers and the Walnut Twig Beetles don’t care. They simply move from tree to tree, breaking through the tree’s protective outer bark layer and leaving behind fungus and viral invaders even smaller than they are, which then go on to sicken and kill the tree. Despite the trees massing millions of times more than a single enemy, down they go, given time.

  1. Be Pretty or at least Useful

This is the road that the Amur Honeysuckle, the water hyacinth, kudzu, and the honeybee took. All of them were introduced to virgin lands where they either forced out the competition, or rode along with humans who were creating a niche until they were powerful enough to convince the whole world that all pollination of food crops relied on them, and them alone, muahaha! Ahem. Honeybees are not a malignant invader, perhaps, but they are nonetheless pushing out native pollinators who were doing a good job before them, and will keep doin’ it after they’re gone (spoiler alert: the bees are not all dying, despite their PR to the contrary. Clever girls, to convince humans that not only are they not highly successful invaders, but they need nifty houses and food and medicine…)

  1. Kill them. Kill them all.

The Crazy Ant (Anoplolepsis gracilipes) took this tactic when introduced to Christmas Island. They ate all the land crabs, and then moved on to other invertebrates and even birds and mammals. Like something out of a B-grade SciFi movie, the kills happen by simply overwhelming numbers of attackers, and because the ants attack and kill the very young in nests and dens where they are unable to fly or run away.

  1. Eat Everything.

Rabbits were introduced to Australia by homesick Englishmen who longed for the fluffy bunnies of soft green hills. Little did they know that bunnies breed like, well, rabbits. Shortly after this, the sparse vegetation of Australia was vanishing into the maw of the insatiable beasts, and everything else started to dry up and blow away, effectively depriving everything else of food and shelter. Mass starvation ensued…. Or something like that. Full-scale war on the rabbits followed, using methods like a really long fence, a lot of shooting, and biowarfare.

So many stories here. And if you want more, check out the list of invasive species here. Not all invaders take the nuclear option, some are more soft and gentle in their approach. It’s hard to fight back against something all the garden club ladies are oohing and aw’ing and planting by the dozen. It’s only fifty years later when their granddaughters are out sweating in the Ohio summer rooting up the ever-damned honeysuckles one at a freaking time that the true evil is revealed.


  1. I think that David Gerrold’s “War With The Chtorr” series provides a good blueprint for how an invasion by an alien ecology can work. (I know–not a popular name in these parts. But give credit where it is due, his background for that series is solid.)

    1. A good background is a nice foundation as long as the story is solid.

      Ecology is a great place to start worldbuilding, but too many ignore it when constructing their worlds in fantasy and SF.

    2. Oh, I think Gerrold is a fine writer. Some of my favorite ST stories have been written by him. He’s just an asterisk that needs a good wiping.

    3. David Gerrold is a good writer.

      When he does write(still waiting on the next Chtorr books)…

      He just has the issue that he believes that because he is skilled in one field, he’s competent in others. And, he has to stay on good terms with the gatekeepers in traditional publication.

  2. Supplant, replace, continue. Seems to be a theme in a few early sci-fi stories. “Invasion of the Body Snatchers” comes to mind for this. Something quiet, insidious, and terrifying.

  3. Missed my favorite “pretty invader” species – the California poppy. Invading all over the world in Mediterranean type climates – while being crowded out of its “natural” habitat by other invaders.

    Hmm. Maybe we should classify it as a “war refugee.”

    1. We get clobbered by various thistles (Russian, Canada and Scotch, among others). Some of these were due to the Garden Ladies long ago. Sigh.

      1. Thistles make me sad. The flowers are so beautiful, it’s a shame that the rest of the plant is so wicked, and causes me to go forth armed with shovel, axe, and extra-strength toxic waste.

        Yes, axe. Y’ain’t gonna get very far with less when the weed is 12 feet tall and pushing 3 inches thick at the base.

        1. ….It never occurred to me there was anything odd about using an ax on thistles.

          Those lovely silver ones with the bright red flowers are gorgeous, but I’m pretty sure the needles can be used as make-shift sewing needles.

      2. I try to get them at the rosette stage, but have had a few up to 6′ in diameter and height. If I have to go mechanical removal, I’ll try a shovel, then a mattock or pulaski. We have some woody weeds, Chamise for one, and a sage that needs a sharp edge to get it.

        The taproot is nasty, but over the years, I’ve found a combination of 2% 2,4-D with a surfactant and blue dye in a spot spray rig works wonders. Haven’t done anything this spring while recovering from eye procedures, so I expect to have a mess on my hands. Life would be easier if the local miscreant didn’t let his back acre go wild in thistles. (The county would intervene, since thistle is a noxious weed, but that route can lead to some nasty reprisals.)

    2. And in the heart of California poppy territory, pampas grass is highly invasive. The local nurseries have switched to non-invasive and native decorative grasses; there’s a lovely purple tufted one that I want. (Well, we have some, but my husband over-planted and it’s out-competed by the lavender.)

      1. I always try to remember that Mother Nature has been running a civil war for nearly four billion years. When we decide to intervene in the conflict, we need to choose our allies very carefully!

  4. My pasture is a battle ground between Chinese Tallow and Box Elder. Both prolific, and fast erroding my dislike of cutting down perfectly healthy trees.

    1. I deliberately planted a confined space with several aggressive species. The resultant plant war is really pretty, and I get a Robin’s nest every spring.

  5. As I have said elsewhere – anybody who thinks Mother Nature is fragile never had a yard to deal with (Moved here 26+ years ago and the yard is slowly winning.).

  6. We don’t have raspberries or blackberries around here. We have black raspberries, mostly along old fencelines (or current ones, thanks to birds sitting on fences or on telephone/electric lines close to fences). We also have mulberries (yum, very non native).

    Russian olive trees (not Russian, not an olive) have tasty berry-sized fruit with lots of lycopene, but it usually ripens in cruddy weather or times when I am too busy. Very invasive, but that is why they were planted by the railroads as a ground cover shrub.

    1. Russian Olive also was used as a wildlife planting decades ago. Multiflora Rose, too.

    2. Russian olive may be regarded as invasive now, but I love ’em. They’re the one tree that manages to survive decades of drought and neglect and still provides a windbreak on the high plains, where you desperately need it come winter. (The wood is also spectacularly beautiful, if not easy to work.)

      State of Montana started to cut down all the tamarisk and Russian olive on public lands… then discovered that local wildlife had adapted to it so thoroughly that this amounted to destruction of desirable habitat. The elimination project is on hold while they reconsider.

    3. In the Sacramento Valley, many of the highways have oleander shrubs planted in the medians or on the shoulders. For those who don’t know, oleander is highly toxic—we’re talking “will kill you if you roast a hot dog on a stick of it” toxic, or “if it catches on fire and you breathe the smoke, it’s like tear gas” toxic. So why is it so desirable along highways? Because it thrives in polluted soil—and it doesn’t release the stuff it takes in. So it happily grows in oil-soaked dirt, and as long as you don’t drive your car-be-cue into it, you get to see some pretty flowers lining the highway.

  7. Cedar, now that you’re an Ohioan, #3 is an example of the inherent ruthless tendencies of Buckeyes. There’s a reason the guys who won the Civil War (Grant, Sherman, and Sheridan were from here. Curtis LeMay also. (Now if our professional sports teams would get the message);)

  8. We owe much to the wisdom of government planners. Japanese Kudzu was imported as a ground cover to fight soil erosion which it does extremely well. Pity no one realized that in mild climates without extended winter freezes its growth rate is phenomenal.
    Then there is the nutria, a large semi aquatic rodent imported into Louisiana as a fur source. Pity no one realized their penchant for burrowing into the side of levees like a muskrat on steroids.

              1. than a lot of the nasty-to-get-food places in Africa.

                OT, but…Caught the latter half of a NatGeo documentary yesterday; one of the crew of a NatGeo exploration team in Africa was eaten by a croc. The rest of the doco was trying to find the croc that killed him (failing to do that) and trying to establish a temporary safe area for the local villagers to be able to wash clothes and get water from the river. The whole thing ended on the surviving crew coming back and drilling a well for the village, because that’s what the guy who got killed would’ve done.

                Returning to topic: pity. Kudzu seems like an ideal crop to grow there in Africa, but if things go on the way they are, really… not even a prolific, hard to kill, hardy food plant like kudzu will save ’em from starvation.

                1. Estimates of Africa’s native population ca. 1900 are as low as 2 to 10 million. The carrying capacity of the continent may be in the billions, but the carrying capacity of the unaided civilizations there is all but absent. If you feed something that can’t feed itself, you get more of it, but you don’t get more capacity for it to feed itself. Africa’s lack isn’t for farmland or easy-to-grow crops; its lack is for people who can consistently do so. I can’t see a crop that grows itself as achieving anything beyond an ever-growing ring of Africans whose sole function in life is to sit around and eat kudzu, until once again it’s eaten down to the bare ground, and now the problem is worse than before.

                  1. Africa’s problem isn’t its people. (Side note, by the way: those estimates are absurdly low, given that in 1904, South Africa alone had 3.5 million black people in it. Where did you get those numbers from?) Africa’s problem is it’s governments.

                  2. Africa’s lack isn’t for farmland or easy-to-grow crops; its lack is for people who can consistently do so.

                    There is a reason that America’s Indian battles were so incredibly nasty. It doesn’t take very many raiders to make farming or ranching impossible– and Africa has a lot of raiding groups.

                  3. Oh, I agree with you there; mind, my suggestion for kudzu was extant the usual African Problem*. It was more that kudzu seems ideal as a plant to introduce as a crop over there, for the wide range of beneficial uses of the plant in question – great for feeding both people and meat animals. NO crop plant will survive simply being predated upon, even kudzu.

                    *Africa’s problem is given the same reason why wells and such are an endless ‘thing you can do to help the community’. You make it happen, and raiders come, get the metal from the well, probably kill villagers and take some of the women and children, and leave. And even if their well was the same kind of old fashioned haul-up-the-bucket kind, the raiders will go after the crops, killing people as they go, to make examples of them. The villagers basically have two choices: die fast from the bullets and blades of the raiders, or die slowly from starvation. Governments have little to no power to handle the raiding problem, or are well corrupt and paid off on local levels to ignore. And this isn’t just in the villages, this obviously exists in the cities as well.

                2. And Kudzu is in the pea family, so it will put nitrogen into the soil, too.

                  The whole thing ended on the surviving crew coming back and drilling a well for the village, because that’s what the guy who got killed would’ve done.

                  Good on them.

          1. Nubian(?) goats are about the only critter that can eat the local thistles. The nitrates will do in any other animals, and the spines discourage casual browsing.

    1. Here in Montana we have wild grape and wild cucumber filling the same niche, nearly as prolific, far more winter-hardy, and equally miserable to get rid of. And the damn wild cucumber’s seeds float away on every breeze.

  9. Amur honeysuckle is the devil. Kinda pretty, but WAY too tough and invasive. I hear it’s dying out in Japan. They can have all of mine.

  10. And, of course, that iconic Western plant, the tumbleweed, is the invasive Russian thistle.

    1. We get them, usually 2′ in diameter, but it’s not listed as a noxious weed in our county. Four named thistles are listed (Musk, Yellow starthistle, Canda and Scotch). Seven others in the sunflower family show up as noxious.

  11. Iowa has a bit of a problem with wild parsley. As a young plant it looks and is tasty and good so sheep get used to eating it. Come late summer it changes and the oils in it cause terrible blisters on the faces of sheep who eat it. Further, it reacts with the sun to blister and burn more. Another technique for all.

  12. One of the idiots who owned our home before we did planted mint. In the ground.

    The only reason it doesn’t annoy me more is because I’m fighting catchweed bedstraw, nutsedge, burclover, thistles, purslane, prickly lettuce, corn speedwell, etc., and that’s even before I have the area of bermuda grass I need to kill off lest it eat my next garden too.

    Bermuda. Grass. If I only had lawn to worry about, it would be fine. But it keeps getting into everything else!

    1. I was told that horseradish should never be planted in the garden because it is impossible to remove. So, I planted it in a pot. It grew out the hole in the bottom of the pot into the yard. Sigh.

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