Pests of ivy geraniums

Question: Parasite of ivy geraniums

Good morning, for some years now I have a problem with a strange parasite of ivy geraniums, that is a small hairy caterpillar that feeds on the buds during the day and at night it hides under the leaves but very often it penetrates into the stems of the plant and inevitably causes its death . How can I fight it?

Answer: Pest of ivy geraniums

Dear Rosalba,
on the geraniums there are always small caterpillars, also called wrinkles, or moth larvae of various types, which generally tend to ruin a few leaves, developing in large quantities only in special cases, and in exceptional years. Unfortunately for some years (the first sighting dates back to 1990) special larvae of a butterfly called Cacyreus marshalli are spreading on geraniums throughout Europe; these insects come from southern Africa, and are now widespread in most of Europe, where they cause significant damage, especially to geraniums. The behavior is different than that of the usual caterpillars, as instead of gnawing only a few leaves, the larvae have the nasty habit of piercing the thin stems and nesting in them, causing the death of various buds, flowers, buds, leaves, and sometimes of whole plants. The eggs hatch in late spring, and the insects become particularly annoying especially in summer. Unfortunately the struggle is not easy to practice, because often, when the larvae are inserted in the stems, they practically go into hibernation, and therefore it is difficult to hit them with an insecticide (since the stem of the geranium protects them) and they do not eat, and therefore there It is difficult to poison them with a systemic insecticide.
In any case, if you can remove any parts that have holes and rotting portions; then treat your geraniums with a product based on imidacloprid, to be used dissolved in the water used for watering. This operation must be repeated especially in early spring and late spring, in order to kill the first larvae that develop. If you don't want to use chemicals, you can fight these insects with bacillus thuringensis preparations.