Fringed Orchid Aphids

2010 January 9

This is why it is a good idea to quarantine new plants that you bring home.


This little bugger is one of dozens that we found on a potted orchid that we were given by a friend (who incidentally raises a lot of orchids). We’d been keeping this new plant separate from our other house plants, not so much by intent as because there wasn’t room with the others. It’s a good thing we did, because once an infestation of parasitic insects like these gets established, it is darned hard to get rid of them.


They were preferentially on the edges and undersides of the leaves of the orchid, and were holding on pretty firmly. That white fringe of wax filaments around the edge made a pretty tight seal with the leaf, which would have made it practically impossible to wash them off.

Once S_ spotted them, we decided that the needs of the many outweighed the needs of the one, and we didn’t want to take a chance on the infestation spreading while we tried to ID the pest. So, the infested plant went out on the porch for an hour. This might sound like a mild step, except remember: we are in Northern Michigan. In January. On the day in question, the temperature was about 2 degrees F [1], or about -17 C.

The bugs (and, unfortunately, probably also the plant) didn’t have a chance.

When we brought it back in, the leaves (which were kind of on the succulent side) went “Tink! Tink!” when they were tapped. If that plant comes back, it will have to be from the roots, and even that would be something of a miracle.

As for the bugs, they were dead, dead, dead. Like this one – it was a bit more mature, and therefore larger, and so when it froze it cracked open, and some of its hemolymph [2] leaked out.


So, anyway. I thought they were scale insects at first, but John R. Maxwell and Charley Eiseman quickly set me straight, largely based on what these bugs were eating. They are Fringed Orchid Aphids, Cerataphis orchidearum. There are two related species in North America that look very similar to these, but they feed only on palms, while this species feeds only on orchids.

I woudn’t have realized that these were aphids on my own, they really don’t look like the classic aphid (bulbous body, spindly legs, and cornicles). The very young stages, like this next one, actually look quite a bit more like mealybugs than aphids, even though they aren’t that closely related.


At any rate, we seem to have caught the infestation in time to keep it from spreading, thanks to the unintentional quarantining. We have a few other orchids which still appear to be clean, and since these aphids are pretty much host-specific to orchids, they are unlikely to infest anything else. We still need to watch out for a while, though. The new-born aphids are the mobile form and wander for a while looking for hosts before they settle down. It is possible that a wanderer will get lucky and find one of the other plants. Although, in the winter the air in our house is dry, and so a wandering aphid nymph wouldn’t have much time before it dried out and died.

Of course, getting a chronic infestation established wouldn’t have been the end of the world, just a long-running nuisance. They can be mechanically squashed or washed off with soap to keep the numbers down, although there’s no guarantees about being able to eradicate them completely. They usually don’t kill the plant unless they are vectoring diseases (either fungus or viruses, usually), and in the absence of disease they just tap off some of the plant juices while secreting honeydew[3]. Still, it’s better just not to have to deal with them.

That’s one advantage to our climate, at least – there is generally a good solution to these tropical plant parasites. Just put them outside anytime in the late fall, winter, or early spring, and they are finished. In the future, though, I think we will need to be more cautious about accepting any plants without a thorough inspection.

[1] Cecil Adams has a nice explanation of why the Fahrenheit temperature scale is so goofy. I liked his summary statement, “In short, 100 means nothing at all on the Fahrenheit scale, 96 used to mean something but doesn’t anymore, and 0 is colder than it ever gets in Denmark.”

[2] Insects don’t have blood as such, they don’t have anything that is distinct from their other body fluids. Instead, they are filled with hemolymph.

[3] A lot of plant-sap-sucking insects (particularly aphids) produce honeydew, which is pretty much just sugar solution. Ants like it, and so they will tend aphids that secrete it, and protect them from predators. It’s practically ranching. As for the aphid making the honeydew, I understand that it is essentially a waste product for them. They need to ingest a lot of plant juices to get all the protein and other nutrients they need for growth, and since they aren’t very active they end up swallowing a lot more sugar than they really need for energy purposes. So, they just sweat out the extra sugar. If no ants come around to clean it up, it just makes a sticky film on the plant that is likely to get black and moldy over time.

6 Responses
  1. January 10, 2010

    These look like a neater, tidier version of the wooly aphid.

  2. January 11, 2010

    Yes, they do, don’t they? The fringe kind of looks like a tiny little tutu.

  3. January 11, 2010

    The photography on this post is fantastic!

  4. January 12, 2010

    Tim, you said these little guys came from a friend who raises a lot of orchids. I wonder if his/her greenhouse is infested?

  5. January 12, 2010

    I’m sure his stock is infested, I already let him know what we found. He had thought that they were scale insects, and that he had them under control.

  6. Kevin Vogel permalink
    January 19, 2010

    I am a graduate student working on aphid biology at the University of Arizona, and your aphids are of particular interest to me. I’d like to discuss them with you further if you don’t mind sending me an email. Thanks!

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