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.

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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.