Geranium butterfly: how to prevent it from affecting your plants

Scientifically it is known as Cacyreus marshalli, but generally any plant user who has planted geraniums will know it as geranium butterfly. It is undoubtedly one of the most common pests of this ornamental plant, wreaking havoc on the plant and killing it in a short time if control measures are not taken.

In this article, we teach you how to identify, prevent, and control geranium or forest moth, as it is also called in some areas.

Common names: geranium moth, geranium moth, geranium borer, african moth.

read more: basic tips for growing geraniums in pots


Characteristics of the Geranium Moth (Cacyreus marshalli)

One of the most common pests of geraniums, a plant widely grown in the mediterranean decoris the moth Cacyreus marshallicommonly called butterfly geranium or drill geranium.

As its name suggests, it preferentially attacks main stem of the plantboring galleries that clog the sap channels, so it can quickly kill a geranium.

The geranium butterfly is a moth of the lycaenid family. Although the first detections were in South Africa, an African country, it has gradually adapted to warm environments like the Mediterranean region and continues to move to colder areas in northern Spain.

The stage that affects the plague is the caterpillar cycle, affecting the whole genus pelargonium and geranium.

When does the geranium moth attack?

Geranium drill actively works with warm temperatures. For this reason, the reproduction of this insect takes place between May and October (spring and summer), initiating the laying at the end of winter.

When the larvae appear, are introduced from the flor (from the corolla of the geranium) inward, biting slowly and feeding on the sap of the geranium. Gradually they drill the stem to the bottom, and practically no visible symptoms are observed until a later stage.

With temperatures above 20 ºCwe can find more than 5 generations of moth per season, which is why control and prevention treatments on geranium must be constant throughout the spring and summer.

Observation Difficulty

An additional problem with the geranium borer, besides the fact that it bores virtually invisible and hard to find galleries, is that he knows how to hide very well.

The size of the caterpillar is more than 1 cm, so it is quite visible to the human eye, but its evolution has allowed it to find a way to try not to be visible. In addition to being green colorusually moves on the back (underside) of leaves, also feeding on them.

visible symptoms

Initial attack state

A few days after the attack, the presence of the geranium butterfly will hardly be noticed. Only, and if we look closely, we will find small entry holes at the gallery. Within days, these driveways rust and take on brownish tones or brown, which contrast very well with the natural green of the geranium.

General damage to geranium with entry holes to perforated galleries. Source: projardin nurseries

advanced state of attack

After 4 or 5 days of attack, one can see a visibly duller geranium, with brown tones and fallen flowers. IF we don’t know the plague we may think we are doing something wrong with the irrigation or the location of the plant, but examining the stem (it is usually soft) and the location of the galleries n will clear up any doubts.

In summary, the identification of the geranium butterfly is carried out in the following way:

  • Hollow rods: to the touch, the affected stems are hollow and flabby. If you break a stem, you will find that it is completely hollow.
  • Flowering problems: open flowers are quickly lost and flower buds do not open.
  • bad look: general rot, fallen leaves and stems and generalized chlorosis.
  • Hole detection: small holes are detected in the stems, which over time turn black and brown.
  • Presence of droppings: at the creation of the galleries, we observe tiny black balls.
Advanced damage with wilting symptoms.

How to Control Geranium Moth

The best way to prevent is to constantly observe the state of our geranium, especially in early spring and with temperatures above 20 ºC, since the ideal conditions for the egg laying and the development of borer larvae.

Control methods

Since the larvae will most likely be found inside the rodsYes, it is important to wet the plant well so that the insecticide penetrates everywhere. Most of the active ingredients used are contact and ingestion, so since they have no system, they must come into contact with the larva or remain until the caterpillar feeds on the plant material.

A preventive calendar in spring and summer, it consists of the application of any insecticide every 15 to 20 days, in foliar spraying. However, if we detect symptoms in the plant, for the control strategy We will do the application every 7 days.

A preventive calendar could be limited to one application every 15-20 days, while in the curative ones the period is reduced, being recommended to spray every 7 days.

Cypermethrin: It generally has low concentrations (1%), at the rate of 3ml/Litre of water sprayed on the whole geranium. Higher concentrations (Cypermethrin 10%) the dose is diluted 10 times (0.3 ml/litre of water). Spray the plant every 7 days until the borer is eliminated.

Deltamethrin 2.5%: dose of 0.3-0.5 ml/litre of water in foliar application on the whole geranium every 7 days. It acts by contact and ingestion (non-systemic).

Esfenvalerate 5% w/v: dose of 1ml/Liter of water applied as a foliar spray to the entire geranium every 7 days until the pest is under control. It acts on the drill by contact and ingestion.

In online stores, nurseries and hypermarkets we can also find presentation formats that can be sprayed directly on the plant, so if we do not have experience in the application against pests we will avoid mix insecticides in the water which can be toxic to the body.

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