Sunday, January 10, 2010

List: Houseplants Which are Highly Prone to Spider Mites

There's no official or definitive list for this; spider mite susceptibility isn't something I've ever tried to quantify. That said, though, there are definitely some plants which are more likely to have mites when you buy them, or more likely to develop a raging case of mites once you get them home.

Thick-leaved succulent plants and cacti tend not to have mite problems; spider mites don't seem to be able to pierce their thicker, waxier epidermises. Consequently, the plants most susceptible to mite attack have broad, thin leaves (like Musa or Dieffenbachia) instead of small, fleshy ones (like Crassula or Hoya). Certain families are apparently also a lot tastier than others; the Araliaceae, Marantaceae, and Apocynaceae seem to be particularly delicious.

(I realize that it would probably be a lot more useful to the reader to present a list of plants which are highly resistant to spider mites, as opposed to plants highly susceptible to them, but that's actually much tougher to do. Even if I've never seen a bad mite infestation on, say, an Aglaonema, I can't really be certain that they're that resistant. Maybe the Aglaonemas with whom I've personally been acquainted have just been really lucky, you know?)

Alocasia 'Frydek.' (also other Alocasia spp.)


Aspidistra elatior 'Milky Way.' (cast-iron plant)


Calathea roseo-picta, possibly cv. 'Rosy.' (also other Calathea spp.)


Chamaedorea elegans. (parlor palm)


Codiaeum variegatum 'Petra.' (croton) (also other Codiaeum variegatum cvv.)


Cordyline fruticosa 'Kiwi.' (ti plant) (also other Cordyline fruticosa cvv.)


Assorted Hedera helix (English ivy) cultivars.


Pachypodium lamerei (Madagascar palm).


Schefflera actinophylla (umbrella tree).


Strelitzia nicolai. (white bird of paradise)


Severity of infestations vary, enough that I really adore some of the above, and refuse to let others in my home. I consider Cordyline fruticosa worth the trouble, and both Pachypodium and Strelitzia are welcome, because they tend not to get out of control mite populations as rapidly as others on the list. Codiaeum variegatum, on the other hand, is a definite planta non grata here, mostly (though not entirely) because of its attractiveness to mites, as are Hedera helix, Calathea spp., and Alocasia spp. All four of those gave us ongoing, substantial problems where I used to work, to the point where I stopped bringing them in. (They've started ordering them again since I left, though, with predictable results.)

Am I missing anything? Let me know in the comments.

Not pictured:
Acorus spp. (sweet flag, Japanese rush)
Adenium obesum (desert rose)
Alternanthera spp. (including A. dentata 'Purple Knight')
Aspidistra elatior (cast-iron plant)
Breynia disticha cvv. (snow bush, snow on the mountain)
Brugmansia cvv. (angel's trumpet)
Chamaedorea seifrizii (bamboo palm)
Cissus rhombifolia (grape ivy)
Colocasia cvv. (elephant ears)
Datura cvv. (devil's trumpet)
Dieffenbachia spp. (dumb cane)
Dracaena marginata (Madagascar dragon tree)
Dracaena thalioides
Gardenia jasminoides (gardenia)
Hedera canariensis (Algerian ivy)
Heliconia psittacorum cvv.
Hibiscus rosa-sinensis (tropical hibiscus)
Impatiens spp. (impatiens)
Jasminum sambac (jasmine)
Maranta leuconeura cvv. (prayer plant, rabbit tracks)
Musa spp. / Ensete spp. (ornamental banana)
Plumeria cvv. (frangipani)
Polyscias balfouriana (balfour aralia)
Polyscias fruticosa (ming aralia)
Primula vulgaris (primrose)
Ravenea rivularis (majesty palm)
Schefflera arboricola (umbrella tree)
Schefflera elegantissima (also known as Dizygotheca elegantissima) (false aralia)
Stromanthe sanguinea cvv.


24 comments:

Anonymous said...

I suppose I have more questions than comments. Number one would be just how much does management of plants contribute to the problem? (Despite the bad rep of Hederas I have had them for years with never a spider mite in sight.) A second question has to do with supplier: since I have a totally organic household I do not spray or otherwise treat houseplants. I may love 'em but I toss them at the first sign of mites, scale, etc. Almost without exception, I find that plants from greenhouses are more likely to have infestations than those from the grocery store (!) or selected big box stores. I won't even buy any more from the famous mail order nursery in CT (name suppressed here but it begins with L) because they arrive with obvious or incipient infestations. How willing are you to nurse a sick plant? How do you prevent your plant spaces from becoming infected and dangerous to new plants? What to do when the heart says wow yes and the brain says whoa up?

Andrew said...

Calocasia 'Black Beauty' is the only houseplant I've ever had develop a spider mite problem. And only after I moved it right beside a heat vent while it was inside for the winter.

(It's also the only Colocasia I've grown, I presume others would be equally susceptible.)

CelticRose said...

Cacti and succulents do get spider mites. The folks on CactiGuide often discuss the best way to get rid of them.

Here's a cactus with spider mite damage. http://www.cactiguide.com/forum/viewtopic.php?t=12688&highlight=spider+mites

mr_subjunctive said...

Anonymous:

Well, it's certainly possible to make mite problems better or worse, depending on how you treat your plants. Cramming a bunch of plants close together so they're all touching, particularly a bunch of plants from the above list crammed together, is a good way to ensure that your mite problems will just get passed from plant to plant to plant, in endless circles. Hot dry air really does make mites much more motivated. Not looking closely at your plants on a regular basis is a good way to ensure that any mite problems you end up having will be considerably out of hand by the time you notice them. Stuff like that.

For me, all of the above is a way of trying to keep infestations manageable, but I assume that such infestations are inevitable, instead of assuming that there will be no mite problems, ever. New plants come in so often here, and a single mite is so easily overlooked, that it's not really realistic to think that I'm not going to bring in new ones from time to time.

People with smaller numbers of plants, and lower turnover rates, have a much better chance of eliminating spider mites completely, or never bringing any in in the first place.

As far as nurseries and greenhouses, well, the problem is that it's kind of my home situation writ larger: any new plant that comes in might be carrying bugs of some kind, and once they arrive, everything's crammed together because we're trying to make the most of our limited display space, so bugs spread pretty freely from one plant to the next. On species which are not particularly good at supporting infestations, this is no big deal, but obviously if the crotons are all next to one another, if one mite lands on one plant, it's only a matter of time before they all have them.

mr_subjunctive said...

Anonymous, continued:

We were also spectacularly stupid about pesticides: we sprayed the same eight pesticides, over and over, in a rotation, meaning that sooner or later we were going to develop bugs that were reistant to those eight pesticides (assuming that the plants coming in from our suppliers weren't already carrying resistant bugs, which they may well have been). So we were getting the illusion of keeping the bug problems under control, but in reality we may as well have been blowing kisses at them, for all the good it did. (When I brought this up, the usual response was, well what would you have us do? We can't just do nothing, and let the resistant bugs breed out of control, either. To which I had no good answer, but I thought eliminating the plants that were harboring the worst infestations, and not ordering more of them, would have been a good start. But crotons sell. Except they don't sell if they're covered in spider mites. Penny-wise, pound-foolish.)

Big-box or grocery-store plants, on the other hand, are thrown out if they don't sell within a week or two, so any bugs that have managed to get a foothold on any plants are eliminated when the plants are. Since they're effectively always starting over from scratch, your odds of getting a clean plant are better. Not perfect, but better. Around here, a lot of the grocery-store plants, especially the bloomers, come from a particular large greenhouse in the area, who I dislike (they were mean to me once). Since they're greenhouse-grown, they did occasionally have bug problems. Thrips, primarily.

I've only done mail-order plants once, from Asiatica, so I maybe don't have enough experience to say anything about that.

How willing I am to nurse a sick plant depends on what plant, what it's sick with, how much it would cost to replace, how long I've had it, whether it still looks presentable, how likely it is that the problem would spread to other plants, and what I would have to do to fix the problem. So I can't offer any rules there, really.

How to prevent plant spaces from being dangerous to new plants? I try to catch everything as early as possible. This is a large part of the otherwise massively-inconvenient and time-consuming kitchen-sink watering I do. If I have to pick it up and take it somewhere, I'm more likely to notice if it has bugs. And if I notice earlier, there's less of a problem to try to fix.

What to do when heart and brain conflict on an already-purchased plant? Usually the brain will give the heart the benefit of the doubt for a while. If it doesn't show visible rapid improvement, then the heart apologizes to the brain, they go out to dinner together and talk, and then when they get home they talk the body into throwing the plant away.

If heart and brain conflict on a potential purchase, heart wins if the conflict is about money (though even the heart has been known to balk at certain prices); brain wins if it's about culture or pests.

mr_subjunctive said...

Andrew:

Yeah, they're all bad about mites. I remembered Alocasia but spaced Colocasia.

CelticRose:

Well, I did say tend not to, instead of are totally immune to. If I were to list every plant that has ever had any mites at all, the list would be much longer. I can't say I've ever actually seen spider mites on cacti, though, with the single exception of an Epiphyllum, once. Are the people discussing this mainly growing them outdoors in a hot, dry, deserty-type area? It wouldn't surprise me if they were more prone to mites outdoors in Arizona than they are indoors in Iowa.

Diane said...

Primula vulgaris. And yet I keep buying them because 88 cents is too irresistible a price.

mr_subjunctive said...

Diane:

Ours at work must have never survived being miswatered long enough to get mites.

Sue Swift said...

Oh how I loathe red spider mite. They just decimate my plants year after year - whether inside or out. There is another "good" mite which you can get though which will eat them. I'm going to try and get my hands on some this year. Not sure I'd want it in the house though ....

Emily said...

I just started battling a spider mite situation on my two palms - an outdoor Ravenea rivularis that had to come in for the winter (NYC) and a Chamaedorea elegans that may or may not have had them before I brought in the Ravenea but definitely has them now. Although who knows, perhaps I have it all wrong and the Chamaedorea passed it to the Ravenea. Anyway. They are both crammed into the fern corner for lack of room, and fingers crossed so far the ferns look okay.

I feel lucky though since I just got back from spending New Years at my sister's place, and when we got down to repotting some of her plants (I know, but she wasn't going to do it herself come spring and several were seriously, death-threateningly potbound) I found a massive, apartment-wide mealybug infestation. We threw out her beautiful yet completely infested Beaucarnea recurvata, already destroyed Gynura aurantiaca (we had already known I was going to have to save it via cuttings before I got there), and pretty severely infested Crassula NOID immediately, much to our mutual dismay, but I think she's going to have to bite the bullet and throw out all the rest and then wait a bit and just start over. Although oddly there weren't any on her Dracaena sanderiana "bamboo" plants that I could see. And they were on EVERY OTHER PLANT in the apartment.

Emily said...

Oh, also, before this palm situation the only plant I've had that I really, really had to buckle down on for spider mites was my Syngonium podophyllum. I've got several different Dracaenas and none of them ever had it badly (I don't remember if they've had them at all, but clearly if they did it was a quick fix), but the Syngonium podophyllum needed concerted effort and I actually almost gave up and threw it out a few times before finally defeating them.

mr_subjunctive said...

Emily:

Yeah, I'd kind of spaced majesty palms too, because they make such bad houseplants that I try to forget they exist. The only two I ever spent any time with (at a previous job) got spider mites pretty bad, fairly rapidly.

The Syngonium actually surprises me, though, because I've never had any bugs problems with mine at home or with the ones at work.

As for mealybugs, throwing all the plants out and starting over is probably the best way to go. It's certainly what I would recommend. Getting rid of mealys on a single plant, when you've caught the infestation early, is difficult enough: I can't imagine it being worth the time and effort it would take to get rid of advanced infestations on multiple plants at the same time.

jodi (bloomingwriter) said...

I've had problems with spidermites on Phormium in the past, but what seems to help with all the plants (besides watching closely) is to mist with a little bit of liquid seaweed fertilizer in the water. That seems to nourish the plants and keep populations down, but this is all anecdotal information on my part. I also have a lot of succulents and avoid plants that are highly prone to spider mites, so that probably also helps as much or more.

Ivynettle said...

I think the only plants I've ever had spider mites on (apart from the ivy collection, before I moved it outside permanently - now it only has aphids, which leave honeydew all over my windowpanes) are Ficus - benjamina, binnendijkii and possibly also pumila (I don't quite remember). And definitely also the carica on the balcony.

Anonymous said...

I think a 'prone to' list is very useful - a you've been warned/possible sad plant suspect list in one. I'm sure everyone has a plant they could add; my hippeastrum and veltheimia usually end up with a mild infestation by the end of the leaves life span. And orchids (get everything...)

hydrophyte said...

Brugmansia are like candy for spider mites. Among marginal aquatics, Acorus are also susceptible. Cyperus seem to be resistant.

Thanks so much for this list and discussion. Spider mites are almost my worst nightmare--just right below home foreclosure.

I remember reading your post about battling mites on Aspidistra. It was sad to hear all of that because they had just prior become my new favorite kind of plant. I will have to be extra vigilant with my new small collection of cast iron plants.

James Missier said...

I have trouble with mealybug - they seemed to be everywhere. I also noticed that they are being farmed by ants!
So, Im still thinking whether to use a pesticide or continue to spray water on them.
The most damaged plants were the Jewel of Opar & wishbone flower.
Other than that, the wax begonia & black flamingo often suffers with whitefly - often happens when the plant matures.

mr_subjunctive said...

jodi (bloomingwriter):

A lot of people on Garden Web recommend fish emulsion for insect problems, so there must be something to the foliar feeding business, but I've never actually tried it.

Ivynettle:

When I worked there, the greenhouse had a big huge Ficus benjamina that was planted directly into the dirt under the greenhouse; there was a little hole in the floor maybe 2-3 feet across. At some point, it got spider mites, and for some reason it never seemed to help much, to spray in there: the tree always had spider mites. Which wouldn't have been so terrible, except that it basically served as a reservoir of pesticide-resistant mites for the whole place. Anything placed near it, or especially under it, would get them sooner or later. They pulled it up shortly after I left, and everybody seems much happier now that it's gone, though it was pretty.

hydrophyte:

Duh. Datura and Brugmansia. I should have remembered that, since mite fear is the main reason I have not yet bought a Brugmansia. WCW had scary stories about them.

Spider mites are a bigger fear than mealybugs? I'm surprised.

James Missier:

Yeah, there's nothing good about mealybugs.

hydrophyte said...

I have one suggestions that I can offer for mite control. Most of my plants are marginal aquatics and mites have gotten into quite a few of them. I have found that an overnight dunk in water will kill off all of the adult mites on a plant. The eggs can apparently live through this treatment, so to eliminate mites from a plant one could repeat as successive batches of eggs hatch and before they can grow to lay more eggs. I have found that dunking a plant once per week 3X can wipe out its mite population.

Of course, many marginal aquatics can withstand a night underwater because they are adapted to live along the edges of waterways. Many houseplants, on the other hand, might sustain leaf damage, or worse, if left underwater for very long. There are however several houseplants that I have been able to treat well this way, including Spathiphyllum and Dieffenbachia. Plants with coarse, waxy leaves ought to be able to withstand this.

Buoyant potting media, such as perlite or chunks of composted bark, also creates problems with this method as it floats up out of the pot to make a mess.

Anonymous said...

Although I search everywhich way upside and down when buying a plant, an apparently clean plant can erupt with insects (scale, mealy bug and spider mites) so suddenly that I assume there are eggs existing in the soil which burst into happy life as soon as the pesticide pressure at the greenhouse is released. My latest horror was a Cyperus which went from astonishingly lush to nearly dead in three days. Some sort of little black beetle? or shiny aphid? in immense quantities. Never saw one before (or again thank god) and I'm sure the plant arrived with them alread installed as eggs/larvae in the soil. Now I worry - should I have composted it? Burned it? Dug a hole 10 feet deep and buried it? (BTW, it's difficult for me to grow Cyperus because my cats love to eat it, love love love munch munch.)

forest said...

I find that nearly all my orchids are susceptible to spider mites. Some more so than others: e.g. phalaenopsis, and Angraecum are mite magnets.

mr_subjunctive said...

forest and Anonymous:

That really surprises me. Even when we had raging spider mite infestations at work, our orchids usually were fine. The only bug problems with the orchids tended to be mealybugs, and then there were a few run-ins with fungus, but never spider mites.

Not saying that you're wrong -- obviously you were there and saw what you saw. I'm just surprised that my experience has been, so far, completely the opposite. What would account for the difference? Supplier? Environment?

Cheryl said...

Impatiens walleriana (the bedding plant) was a common houseplant where I grew up. Spidermites apparently love the heck out of it.

Keith said...

My conservatory is now full for the UK winter. I thoroughly sprayed and scrubbed it twice, yet already the dreaded mite has returned on my Erythrina Crista Galli!This was affected last winter, and again whilst outdoors early this summer. However, it was mite free for the best part of three months.
However, the Erythrina hated the most effective spray in the summer, so I couldn't risk it. So it went out overnight in three degrees of frost.
It can go dormant. What it can't do is share them around! I have three Sollya heterophylla, two Clerodendrum, Hibiscus, Strelitzia and Tibouchina in there. Not to mention a cat, which has got to help spread them around.
I'm desperate to get this Erythrina into bloom next year, and a head start in the conservatory will be a great help. But it may just have to go in the garage if this problem persists!