Olive
Purple Mussel Scale
Lepidosaphes beckii
Insect
In a Nutshell
- Oval, flat, purplish brown insects that look like tiny bumps on the plant surfaces.
- Green spots on fruits where the insects feed on.
Can also be found in
Olive
Symptoms
Purple mussel scale insects attach to the surfaces of plants, including fruits, leaves, twigs, and the trunk. They feed on the plant's sap, which leads to several visible issues. Ripe fruits start to turn green where scales feed. Leaves turn yellow and may fall off the plant. In severe cases, the ends of branches might start dying and this damage can spread backwards towards the main part of the branches.
Recommendations
Organic Control
Spray trees with dormant oils and lime sulphur in late winter before the first eggs hatch or if you spot the infestation early. For smaller trees, or on reachable parts of larger trees, you can scrub off heavy build-ups of scales using a plastic dish scrubber. Normally, natural enemies keep these insect populations in check, so they're not usually a big problem.
Chemical Control
This insect usually causes minimal damage, but in large numbers, it can cause severe harm, potentially requiring chemical control. These insects are tough to kill with insecticides once you notice them because their hard scales protect them. The best way to control them is to treat early in the season when the young, unprotected insects are moving around before they settle down to feed. It is best to avoid using strong, broad-spectrum insecticides, like synthetic pyrethroids, because they can kill these beneficial predators. Prefer to use insecticides that can be absorbed by the plant.
What caused it?
The bumps on your plant are adult female purple mussel scales. They do not move and hide under a purplish-brown protective cover. The female lays eggs under her protective scale, where they stay safe through the winter and hatch in late May or June. These insects reproduce once a year. Young insects can move and spread to new plants by walking or being carried by the wind, vehicles, animals, birds, and people's clothes. They can also spread through plant material that carry the insect on them.
Preventive Measures
- Use pest-free materials.
- Keep plants healthy by providing them with enough water and nutrition helps them resist pests.
- Regular checks for scale insects in orchards are necessary.
- Don't forget to check the undersides of leaves or young stems for adult insects, particularly in shady or sheltered spots.
- Early detection is crucial! While you can easily see the adult insects with the naked eye, younger insects are harder to spot.
- To detect the first generation of young insects, wrap double-sided sticky tape around the twigs of trees that were previously infested.
- The young insects are tiny, flat, transparent, and have thin legs.
- Check the tape every other day to see if the young insects are stuck to it.
- If the tape gets wet or dusty, replace it.
- Alternatively, you can hold a white piece of paper under the branches and tap them with a stick.
- The crawlers, which could be white, yellow, orange, or purple, will fall and show up clearly on the white background.
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