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Geranium Moths in a Spanish Garden • Ian


Can you suggest any economical way to stop the geranium moths devastating my plants? 4 weeks ago my garden (mostly in pots) looked really lovely, I've fed and nurtured all my garden, but the moths keep coming back. I have sprayed them with the supposed moth spray, but apart from costing a fortune which I can ill afford, my garden has been destroyed by these pests. I am at my wits end to know what to do, so if you could please suggest something I would be eternally grateful.

Thanking you in anticipation

Mary McGill


Hi Mary,

It sounds like the culprit is either the Geranium Bronze butterfly (Cacyreus marshalli) or the Geranium plume moth (Pterophoridae species). Plume moths are easily recognized by their characteristic "T"-shaped resting posture. Often they resemble a piece of dried grass, and may pass unnoticed by potential predators even when resting in exposed situations in daylight.  

 Geranium-geranium_bronze_butterfly  Geranium-geranium_plume_moth

However, they both operate in much the same way: The small, yellow-white eggs are deposited singly any place on the plants, but are usually laid on newly forming flowers or on the underside of leaves. Hatching occurs in 2 to 3 weeks. After emerging from the egg, young larvae (caterpillars) mine in leaves and later burrow into the stem, petioles, flowers, or seed pods, where they feed and develop. The larvae vary in colour between yellow and green, with stiff white hairs, and sometimes have pink markings along their body. The caterpillars later form pupae that hang upside down on the plant or are found within plant stems. The adults are weak fliers and usually remain on or near the host plant.

   Geranium-caterpillar_at_work__1  Geranium-caterpillar_at_work__2  Geranium-caterpillar

If you have enough of your plants that are worth saving, then this is what I recommend:

-       First, isolate the infected plants to keep the problem from spreading.

-       Continue to remove/cut of any infected parts (including infected stems).

-       Pick off any of the caterpillars that you see by hand.

-       The rest may be killed by spraying regularly.


Spraying will not kill the moths (unless they are on the plant at the time) but it kills the caterpillars before they can burrow into the stems and damage the plant. Any spray that claims to kill caterpillars (orugas) should work.


I have heard that “DECIS” from Bayer works well. It comes in a very concentrated form which you dilute and spray with a hand sprayer. Other products are "Insecticida Polivalente" from Compo and any Bt sprays.Bt(Bacillus thuringiensis) is a naturally occurring bacteria that causes disease only in the larvae of moths and butterflies.


Or you can try some of the following homemade, inexpensive sprays:


Insecticidal Soap Spray:
1 to 2 tablespoons liquid soap
1 L water

Combine ingredients in a bucket, mix, then transfer to a spray bottle as needed.

Soap has been used for centuries as an all-purpose pesticide. It disrupts insects’ cell membranes, and kills pests by dehydration. Note: A liquid soap or soap flakes are more efficient than detergents.


Garlic and Red Pepper Spray:

Cut up one unpeeled onion and one unpeeled head of garlic. Add with one heaping tablespoon of red pepper to three pints water in a saucepan. Cook about 20 minutes on low heat. Let the spray cool. Pour it in glass jars and cover with a lid. It will keep in the refrigerator over a month (or freeze it). When you are ready to use the herbal spray, use one tablespoon per pint of water. Use it alone or add it to the soap spray.


Wormwood Spray:

The plant itself is a deterrent to slugs and snails. It can be made into an effective herbal insecticide spray against slugs, snails and caterpillars. To make wormwood insecticide spray, simmer leaves in at least three pints of water. Strain, cool and store in glass jars. You may add soapy water to increase effectiveness.


Pyrethrin Insecticide:

Pyrethrin, a natural insecticide found in some plants, is relatively nontoxic to humans and pets. A natural source of Pyrethrin is the Crysanthemum plant. To make a home-made garden bug spray soak crushed or cut up chrysanthemum flowers or leaves in a bucket of water for 1 day, filter through cheese cloth or an old pillow case, then pour in a spray bottle.


Be aware that most of these recipes have little residual effect and must be used frequently and regularly to control the caterpillars. Insecticidal treatments should be repeated every 2 weeks to disrupt the life cycle. Apply on an overcast day or in shade (to avoid scorching). Apply on the entire plant, especially under the leaves. Alternating insecticides used in pest control efforts will help reduce the chances of the pest developing insecticidal resistance.


As for saving your plants, I would wait to see how much remains after you treat the problem. If the plant still looks like it will thrive, then repot it in fresh, good, potting soil. Be sure all of the damaged parts are removed.

To prevent it from happening again, use a fine net over the entire plant or repetitive spraying of insecticide. Also dead-heading regularly will help. Good luck with it.


Marc Vijverberg and Gurli Jakobsen

638 180 284
659 880 444

Guardamar del Segura



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