Monday, November 17, 2008

Question for the Hive Mind: Exciting New Insect Pest

Particularly proud of this picture: I got it by photographing a hand-held magnifying lens with a hand-held camera in front of a wobbly Sansevieria and still got something approximating clear focus. Of course I also had to take ten pictures, too.

We got a new batch of tropicals in from Florida on 6 Nov., and found some of these on this one Sansevieria trifasciata. This is not the first time I've seen these; they're the same bugs (pretty sure) that were on my Trojan Sansevieria (story is at the whitefly profile, even though I've since concluded that they were not whiteflies).

The above is the best picture I'm capable of getting. Normally you can't see that much detail.

We've seen these on a variety of things, most of them relatively new arrivals:

Sansevieria trifasciata 'Laurentii,' 'Hahnii' (snake plant / mother-in-law's tongue)
Zamia sp. (cardboard palm)
Dracaena deremensis 'Janet Craig Compacta'
Dracaena deremensis 'Limelight'
unknown palm (I wasn't present when the infestation was diagnosed)
Cereus peruvianus (pic below)
Agave lurida

It took a while to conclude that they were probably coming from Florida, because, you know, you hate to make these accusations unless you've been watching the plants in question really closely. They seem to be easy to get rid of on Dracaena and more or less impossible to eliminate from anything else, no matter what you spray or how often you wipe off the plant or what you use to do either of those things. The damage seems to be mostly aesthetic: when removed, the bugs leave yellowish spots where they were, which are permanent, but thus far none of the plants affected have looked like they were in imminent danger of dying.

Particularly bad batch on a Cereus peruvianus. There's actual scale in this picture as well, which I think is probably not related but might be.

I sent a picture to our supplier, who checked with the grower, who claimed that they'd never seen these before and they'd have to get back to us about what they were. Which I suppose might not be a lie, but I am deeply skeptical.

So. Anybody (especially anybody in Florida who might be a little less clueless than the growers) have any ideas? The last time I spoke to her, the supplier said the growers think it's not scale.


Anonymous said...

Are these motile? They look really similar to something I had on my Sans for awhile and thought was some kind of scale or mealybug, and were pretty much causing the same kind of damage you described, although they were causing the leaf tips to die after awhile, as they were congretating there and multiplying unchecked without me noticing.

mr_subjunctive said...

They must move around at some point, since they can be found invidividually around the plant, as well as in clumps like this. I also noticed, when I looked more closely at this plant, that they tended to congregate in scars and splits in the leaves.

Once they reach visible size like this, I don't think they move around any, but obviously it's kind of difficult to know for sure: radio collars don't stay attached very well.

MrBrownThumb said...

I have no idea what they are but I've never heard of Sans being bothered by pests.

on a side note; I'm seeing toy microscopes for sale this year for Christmas and I've been thinking of getting one to see if I can use it to do "macros" like this of bugs. Good job on the hand held.

handofthesly said...

I am not 100% on this but I've seen very similar on the boysenberry plants at work.
Best I could come up with was Euonymous scale, what do you guys think?

mr_subjunctive said...


Best match I've seen so far, so until/unless I run across something even closer, euonymus scale is what I'm going to call them.

(Should maybe note for the record that this is a seven-year-old post, and I don't think I've seen them since, so they must not like most tropicals or houseplants very much.)

handofthesly said...

I realise this is an old post. I'm still reading my way through them from the beginning each day before work, only up to 11/08/2008!

This may not be Euonymous scale, Unaspis Euonymi, per se. It definitely looks like some sort of Unaspis though.

It's strange I've only ever seen them feeding on the canes of our berry fruit plants here in New Zealand. It appears that the thin white scale insects we are seeing the most of are the males of the species. Not sure if I've seen any females, which supposedly are darker in colouration and oyster shaped, or juveniles for that matter which are significantly smaller, ovoid and orange.

The Citrus Snow Scale, Unaspis citri, was a serious problem in Florida citrus groves in the late 1960's. I'm hoping the ones we have here aren't this particular species as the berry fruit are close to our citrus plants. I haven't seen any on the citrus yet!