Scale insect on healing onion

Asked April 17, 2018, 3:27 PM EDT

We have a mature healing onion, attacked by what looks like scale insect. There is a small sack in a web and insects outside, it is sticky, and the onion has clearly been pierced. The leaves are crushed for treating wounds so wiuld like to something not toxic to people or to the resident cats who find the onion tasty.

Montgomery County Maryland houseplants scale pest insects and mites healing onion ornithogalum caudatum pregnant onion

3 Responses

This sounds like the plant Ornithogalum caudatum, also known as Pregnant Onion for the way that the bulb sends out bulblets right through it's skin.
It does look like it has scale.
We suggest removing the sack (perhaps from spider) and using your fingernail to dislodge and squish all of the scale insects you can see. Use small manicure-type scissors to trim off any dried, dead or dying plant material, and be sure to inspect carefully as these often attach in tight crevices between leaves.
Ants can actually 'farm' scale insects. Introducing them and eating the honeydew, stickly sap material they can excrete.
Wipe down the whole plant with a damp cloth.
You might want to investigate further whether the cats should eat this plant. It's not supposed to be edible and could be poisonous.

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The onion does produce bulblets under its skin. Used by the Pennsylvania dutch ;comes from there. We want to repot in a hanging pot and keep awY from cats. I used alcohol and swabs to remove insects on surface. Sure there are more betwwen the leaves. Anything that will kill them?

This is tricky.
Here is our page on scale on houseplants:https://extension.umd.edu/hgic/plants/scale-insects-houseplants

The thing is, anything you use- least toxic being insecticidal soap or oil (labelled for houseplants), then moreso a systemic that is absorbed through the roots to protect the whole plant, might show up in the sap that you wipe on your skin.

Do you have any baby bulblets or smaller onions already showing that you could plant up and get rid of this one?

At the very least, you could try putting it outside for the summer (keep the sunlight and watering the same) and hope that other beneficial insects keep the scale in check. The settled scale covers you are seeing and disposing of are actually like shields covering lots of eggs. At some point they will hatch and become "crawler" stage and then move around the plant and reproduce again. That would be a prime time to control them whatever way you choose. You could use sticky tape or cards to monitor for their emergence.

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