What is this mass of white bugs?
July 6, 2010 6:09 PM   Subscribe

What are all these little white bugs on my mustard green plants?

I just noticed that theres thousands of little white bugs all over the tops of my mustard green plants. They look like sesame seeds and don't seem to be able to fly nor do they really move around - I've tried spraying them with water.

Are they dangerous and should I cut down the plant and toss it? The plant is on my balcony and fairly near my windows.

posted by wongcorgi to Science & Nature (6 answers total)
posted by disillusioned at 6:12 PM on July 6, 2010

They've already bolted, so unless you're aiming to save seed, pull them out.

Without a closer pic, ID is probably going to be impossible.
posted by ryanshepard at 6:20 PM on July 6, 2010

posted by changeling at 6:35 PM on July 6, 2010

Yeah, could be whitefly nymphs, which don't move. I'm in the middle of trying to stop the bastards from taking over my front and back yards. They seem to particularly love my strong-tasting plants like mint, lemon balm, and epazote.

People do throw out entire plants if they're badly infested. For future reference, spraying the whiteflies and the soil with an insecticidal soap solution every few days (to make sure you get the ones you missed the previous times) will kill them and the eggs and won't make your greens too toxic to eat. A few places also recommend "work earthworm castings into the soil, to make the plant healthier so it'll be less susceptible to pests." I'm going to try that shortly.
posted by cybercoitus interruptus at 7:36 PM on July 6, 2010

Bit sure about whiteflies, since they, well, fly, and typically live under the leaf. I've never seen the nymphs on top of the leafs either, but I'm no expert. In any case, it's likely some sort of sap sucker, and most of them fall prey to a couple of mostly non-toxic solutions (no pun):

- Insecticidal soap based sprays (effective but not persistent, use several times over a few weeks)
- Neem oil based sprays (my preference)
- Nicotine based sprays (cheapest...take an old cigar or a couple of cigarettes, put it in a spray bottle full of water, soak for a week and spray the buggers)
- Orange based sprays (never tried them)

I've been using soap+neem with seemingingly good effect the last two seasons.
posted by kjs3 at 8:35 PM on July 6, 2010

Are they dangerous and should I cut down the plant and toss it?

Dangerous in what sense? It's impossible to tell exactly what they are from that photo, but it is likely they are aphids or whitefly nymphs, which suck sap out of plants and can disfigure and stress them. However, those mustard plants are on their way out anyway. You can blast the bugs off with a jet of water, spray with liquid dish soap (1-2% in water), or wipe/squish with your fingers if you want, but unless saving seed I would just compost those plants.
posted by oneirodynia at 3:28 AM on July 7, 2010

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