Tuesday, February 5, 2013

In Which I Nearly Achieve Houseplant Pest Bingo

There are too many plants in the basement, and too many plants needing water elsewhere in the house, for me to have been able to check everything in the basement this week. But here's where things are since my last post about the Great Purge of 2013:

I've discarded 125 more plants, 70 of which were Anthurium seedlings.

This is both worse than I had feared, and not nearly as bad as I had feared. I'd assumed that I would find a handful of locations that were just swarming with scale, but most of the collection would be clear. The reasoning was that there would be a lot of insects near the spots where they were first introduced, but since they don't crawl very far or very fast, they wouldn't have had time to spread very far away from those initial sites. And that actually is more or less what I found among most of the collection -- a few hot spots, but mostly clean. However, among the Anthuriums, it was basically the opposite: lots of plants that only had one visible insect, occasionally two, but no plant that was heavily infested, and the affected plants were sort of randomly scattered around the flats of seedlings. I don't know what that means, exactly, but it must mean something.

I also discovered, in the process of giving everything close inspections, that I have thrips. For sure. I'd thought this was possible, because I've seen damage on a few plants (especially the Anthurium seedlings) consistent with thrips, and on two occasions, I've seen fast-moving skinny insects that might plausibly have been thrips, but 1) they're so fast that by the time I realized that I had seen something, the something was no longer there to see, and 2) it's only happened a couple times over a long period of time, so by the time I saw the second one, I'd mostly forgotten about having seen the first.

As far as it goes, I only saw two thrips on this round, but I got a better look, and one thrips1 actually held still long enough to be identified (though not photographed). So it's been confirmed.

Which means that, among other things, I have finally reached the point where I have had all seven of the major houseplant pests,2 which feels like an accomplishment of sorts. I have not yet gotten Houseplant Pest Bingo, see below, but am now in a position where I'll almost certainly have Bingo with the next pest I see, regardless of what it is.

Slugs, earwigs, caterpillars, snails, root mealybugs, or borers/weevils would all get me a Bingo. And then I win! (Something!) C'mon, caterpillars!3

Most of the scale sightings were of the same species over and over again, which is what I'd expected. The species in question is nearly circular, brown, and very flat, and what makes me think that it's the same species consistently is that unlike most pictures of scale I've seen, on this one the legs are almost always visible through the shell. (In fact, seeing legs is as good as the squishability test, as far as determining if a random spot is scale or just a scar.)

The species of scale I've been seeing on everything. Left: younger one, on Eucharis grandiflora. Right: a couple more mature individuals on Alworthia 'Black Gem.'

However, I think there may be more than one species in the basement, because I found one plant that had these instead:

Many unanswered questions about this. Where did they come from? How did they get to be so huge without managing to spread to the plants around them? (I was being awfully thorough: if other plants had these, I would surely have seen them.)

But so the point is that in the course of trying to get one problem under control, I've discovered two more problems. Which is less depressing than you might think, because the stuff I was already planning to do should also get rid of the thrips and the new scale. The imidacloprid may yet do something, and I've decided to go ahead and keep spraying the Anthurium seedlings with neem oil, on the theory that it can't hurt, and may help. Plus I'm about to begin another sweep through the basement to check for scale (or whatever), and anything that has scale, or a major problem with something else, will be thrown out. There may be no magic bullet, but perhaps there's a magic shotgun shell.

As far as losing plants that cannot easily be replaced, there have been a few, but not as many as I was expecting. Most of the hard-to-replace plants were thrown out because they'd never done well for me, not because I saw scale on them. The only plant that really qualified as a sad event was a NOID Nematanthus with pink/orange blooms, where I lost all five plants I had. I also lost both the Murraya paniculata I'd propagated from a cutting, and the one I'd propagated from seed.

And then there were the three that I should have thrown out, but cheated and kept parts anyway:

1) I threw out the parent, but propagated an Epipremnum aureum 'Marble Queen' that had belonged to the husband long ago. It didn't seem like it was that badly infested, and although 'Marble Queens' are easily replaced, this specific 'Marble Queen' wasn't. I washed the cuttings off (including power-washing with the sprayer attachment set to "annihilate"4) and am water-rooting. I'll check them over a few times before potting them up, but considering the plant's history, I didn't want to get rid of it completely.

2) I also propagated Agave lophantha from offsets, after power-washing, though I did it kind of backwards. The main plant didn't have visible scale on it, but the offsets did. The weird part was where. My A. lophanthas have been producing lots of offsets (at least ten per plant) on long, skinny stalks, with thin, stunted leaves shielding the stalks all the way up. After the stalk is a certain length away from the soil, the offset starts growing thicker, heavier leaves, and settles down into a rosette form like the mature plants have.

I didn't think to take any pictures of the runners that had actual offsets growing at the end. This is a picture of one of the long, skinny stalks with the thin, stunted leaves, though.

On my plants, the parents were clean, and the thicker leaves of the offsets were clean, but there were scale hiding under the thinner leaves up the stalk.

This makes it sort of silly of me to spare the offsets, and there's a good chance that the scale kept appearing on the offsets because they were crawling over from the main plant, maybe beneath the soil. But, the parent plants had grown large enough to be dangerous and unwieldy, and I didn't want to throw out the entire plant, because I don't see them for sale very often. So power-washing the offsets and then potting them up was sort of the best compromise I could manage. I get to keep the species while shrinking it to something more manageable, and hopefully any scale present was either discarded along with the stalks and parent plant or washed down the drain during the power-washing. If scale show up on the offsets later, I suppose I'll throw them out, but I'm hoping the scale will let me get away with cheating, at least on this one species.

3) The non-variegated Agave americana was also spared. Again, the parent plant seemed to be clean, or at least cleaner, but the offsets had scale. So I pulled the offsets out, threw them away, and kept the parent. This is probably kinda stupid, but the plant has only just started to get big enough and healthy enough to resemble a full-grown plant: I didn't want to have to start all over again if there was any way to avoid it. And I have a soft spot for Agaves anyway.5

Pot diameter: 5.5 in / 14 cm.

So, overall, it was worse for the Anthuriums than expected, but better for everything else. There were several borderline cases, where I saw honeydew spots but couldn't actually find insects, so I don't know if those plants were infested or just near plants that were. So there will probably be more plants on the way out this week, when I recheck. Also, this round of inspections only covered the south and east sides of the basement; I have another 57 plants on the west side that need to be checked for the first time. But so far, things aren't terrible.


1 "Thrips" is one of those words that is both plural and singular. One thrips, two thrips. There is no such thing as a "thrip." It's especially confusing in this case because the words that do this don't generally end in "-s," so it seems like there ought to be a "thrip." But there is not.
2 (spider mites, aphids, scale, mealybugs, whitefly, thrips, fungus gnats)
3 Also: I'm not 100% certain about the viruses, since I've never had that checked out by a lab or anything. But I've seen enough things that I thought could be viruses that I figure one of them probably was. The most recent has appeared on one of my seed-grown Aglaonemas:
As with the other occasions, I can't be positive that there's a virus here, but a Google search for "ring spot plant virus" turns up a number of photos that look like this. I haven't thrown the plant out yet, but I realize I probably ought to. Maybe in this next round.
4 It's one of those garden-hose attachments with multiple settings. The settings are something like: mist, gentle shower, cone, jet, pulse, julienne, stun, liquefy, annihilate. For watering, I pretty much only ever use mist (for seedlings) and gentle shower (everything else), but when I feel the need to really blast the hell out of something, I use one of the others.
5 Indeed, from the perspective of the Agaves, I am nothing but soft, stab-able spots.


Jin Wicked said...

If caterpillars ever show up in my houseplants...
Oh God. I will just burn it all down.

mr_subjunctive said...

I figured caterpillars would be the easiest to spot and remove, of the pests that would get me a Bingo.

Though really, I would be fine with anything but root mealybugs. I am terrified of root mealybugs.

Davelybob said...

I wonder if the nematanthus you had to pitch was the same one I got from you two years back. If so, I can start more for you and send with the black gem once you sound the all clear. Mine is flowering like mad right now, so I will try to remember to get a picture tonight to confirm, but that sounds like the color of the flowers I have.

orchideya said...

You are far ahead of me in that Bingo game, but then I never had SO MANY plants.
My worst pests are red spider mites attacking my slippers from time to time. I can never spot those damned things but find ugly signs of their presence that permanently damage the leaves.

Liza said...

I wonder how thrips could've made it into your basement?

I'm impressed that you're still able to have a sense of humor after what you've been through.

I've been playing the blame game with my houseplants, trying to determine which one brought the mealy bugs. At first I blamed my Nematanthus, which was the only new plant I had bought in ages. (I threw it away over the summer.)

But now I'm thinking the Gardenia that Dottie gave me is the real culprit. I haven't given up on it yet - in fact, it has buds forming - but it's such a bummer! How will I explain that to her?

Dang bugs!

Paul said...

Doesn't sound like it is as bad as it could have been.

That one plant leaf you showed definitely looks like it has ring spot.

Paul VA said...

I never knew you had a thing for Agaves. They're my favorite type of plant. My Agave lophantha offsets exactly like yours. lophantha are super hardy too, you might just be able to take it outside.
Ive only had thrips on african violet flowers. ive never even seen them on anything else

mr_subjunctive said...


On the thrips, I have no idea. The first sighting was on the Rhipsalis NOID on the west side of the basement, quite a while ago, and I can't remember the details of the second. It was long enough ago that I have no idea what plants were new additions at the time, so I'll likely never know where the thrips came from.

As to the sense of humor, I've been feeling so much better now that I've given myself permission to just throw plants out. We're not yet at the point where it's made my actual workload lighter (I actually have to spend more time dealing with the plants these days.), but things have definitely improved.

mr_subjunctive said...


I wound up throwing that plant out last night, after noticing that the ring spots were no longer confined to the one leaf.

And no, it's not as bad as it could have been, at least not yet. (There are still ~60 plants yet to be checked, and a re-check of the Anthurium seedlings last night found another three cases of scale. So more plants are on the way out; it's just going to be happening a lot slower.)

mr_subjunctive said...

Paul VA:

The Agave lophanthas actually spent the summer outside last year. The hope was that the scale would disappear because outside is magic.

Davesgarden.com says they can only go to 20F/-7C, so I might be able to put them outside in late April or early May. I'll probably wait, though, 'cause I don't necessarily trust davesgarden.com a lot on that sort of thing.

My fondness for Agave has varied somewhat, but I really liked them in 2010; most of the ones I have were purchased then. (A. americana and two different variegated versions of same, A. bovicornuta 'Reggae Time,' A. desmettiana variegated, A. lophantha, A. titanota, one of the three kinds of A. victoriae-reginae I have)

I've gotten some more recently, though. A. attenuata 'Kara's Stripes' (May 2012), A. NOID hybrid (May 2012), A. victoriae-reginae 'Pinguino' (Jan 2013), A. vilmoriniana (June 2012).

I would really like Agaves if they were more scale-resistant, obviously, but I've been pleasantly surprised at how well they've adjusted to life indoors, even when I'm not able to give them any direct sun.

I've seen thrips before at the ex-job, on some Gerberas and on a Farfugium. Presumably I've been around plants that had them a lot more often than that, but they're tough to spot directly.

Anonymous said...

'Where did they come from?' Oh Mr.S...sweet, silly Mr.S. I hear this question every day at work when customers bring me their buggy, infested plants. 'Why?' they clamour. 'How did this happen?' they beseech me. Back in the day, I used to get really hung up on this, and I would point out the fact that their act of bringing in the bugs was exposing the entire greenhouse to contamination. I didn't mince words - I was mighty fuckin shirty about it. And the customers were contrite, you betcha.
But that didn't truly answer the question.
I've become a little more philosophical about it all and now I tell them: 'Bugs are everywhere - it doesn't matter whether you're in a basement apartment or the 54th floor of a condo. If you even approach the right conditions, bugs will put in appearance. Life will find a way. Plants have evolved many ways to deal with bugs but a potted 'captive' plant is entirely dependent on you. Provide light, water, humidity, nutrition, temperature fluctuation and air movement and behold a happy, powerful plant. A plant that thrives and flexes and sends out powerful 'fuck you' vibes that sends bugs scurrying for amenable quarters.' And then I sell them some insectcidal soap or other bullshit and feel like an asshole. Because the truth is, (as I think you're coming to realize) these poor plants are not meant to be indoors. I'm as conflicted as an elephant keeper in a northern zoo facing the wrath of Bob Barker! On the one hand, it's my livelihood, and I adore plants, the more exotic the better!, and on the other, I have to bow to the hippie adage 'if you love something, set it free'.

I guess what I'm saying is, it's up to you to control bugs by exerting control over the artificial environment the hapless plants find themselves in. If you can't recreate ideal conditions for them - don't despair! Let me direct your attention to these amazing 'Sticky Stix'. And some horticultural oil and a moisture meter, some fertilizer, new potting mix - a new pot! how about some grow lights?

It's all such bullshit and I'm just a whore of the industry.


Diane C said...

I hate to think of any bugs in the house at all. That said, is there some other bug you could set loose to help control them, like maybe a spider or two?

Pat said...

What a drag about the Anthurium seedlings. :(

To help spot thrips if you suspect their presence breathe on the plant gently but heavily. This makes them run around manically and writhe.

I have had scale, mealy bug, root mealy bug, psyllids, spidermite, thrips, fungus gnats, mildew, weevils, aphids, wilt, slugs and whitefly over just the last twenty years of houseplant raising. At the moment I appear to have nothing at all.

I was particularly proud of the psyllids as they were a species that specialises in the mint family and must have been very happy to find my Plectranthus collection.

Surely centipedes are not a plant pest? They are all carnivores. Springtails and earthworms are usually unsightly but not a problem. Springtails may nibble seedlings but that is your own fault if you are overwatering that much.

mr_subjunctive said...


Very impressed. Psyllids!

Centipedes aren't a plant pest exactly (nor earthworms, as far as that goes), but people do occasionally find them in potted plants, especially potted plants newly arrived from Florida. And then when that happens, people tend to freak out about it.

I have springtails at the moment in one of the containers I'm using to germinate Anthurium seedlings. I can't let the vermiculite dry out, because then the seedlings will die, but I can't let the springtails just stay there, because then the seedlings will die. I've tried sprinkling in a little bit of the imidacloprid granules, though I was perhaps overly cautious about how much imidacloprid because I didn't want to upset the seedlings. So the springtails stayed. Tried a couple squirts of neem oil, too, and haven't re-checked since then, so I don't know what the situation is at the moment.

mr_subjunctive said...

Diane C:

There are such things, though I don't know specifically which insect-eaters are out there or how useful they'd be against scale. Also, now that I've dosed everything with imidacloprid, it would maybe be a waste of money to buy something to eat the pests.

mr_subjunctive said...


In this case, "where did they come from" is not really the question I'm interested in so much as "where else are they."

Though I would also like to know where they came from, 'cause it's weird for them to have wound up on a single plant in a shelf full of plants, and no others.

I'm certainly not coming to realize that the plants should be outdoors. There are plants that I shouldn't have at all, but: I have the conditions I have, and I exert the effort I exert, and the plants can either do well in that situation or not. As irritating as the pests are, and as distressing as the whole situation in the basement has been, there are still plenty of plants, even now, that would qualify as All-Stars. (There was going to be a post about this, and then The Awfulness happened and I decided I didn't want to spend that much time thinking about plants. But I might try to resurrect the idea, if I continue to feel good for a while.)

Would also like to note for the record that plenty of plants get bugs, look shitty, and die in their natural habitats too. Or outdoor cultivation, for that matter.

Jonathan said...

On the A. lophanthas, I can testify that they are fine at least down to 25 degrees, but they do like a bit of hardening off in cool temperatures first.

Martin O. said...

I am not sure if that helps you at all but I successfully dealt with a thrips invasion last summer - and I didn't use any chemcial weaponry to get rid of them.

I had 4 lemon basil plants (Ocimum citriodorum), which I occasionally put on my windowsill (I am living in an apartment building), because their wonderful smell attracted all kinds of flying insects (small wasps, bees) and it was quite a show to see them all buzzing around the plants.

In any case, they also attracted a large number of thrips which settled on their leaves. Bad enough, they also stuck to my nearby coffea arabica plants and even went through different rooms in my apartment, so I found individual thrips on some Fittonia plants.

I made then a habit to search each affected plant every evening for thrips and if I found any I would spray the leaves with water and if necessary kill them with my thumb. Four weeks after the start of the operation, they had vanished.

Interestingly, a number of them tried to migrate onto my cherry tomato plants. That happened to be a death trap, as I later found a large number of dead thrips on their stems. My fierce tomato plants had evidently killed them all.