The scale insects, also known as cochineal (Coccoidea Handlirsch) is a plant parasite belonging to the order Rhynchota, suborder Homoptera, and specifically the section Sternorrhyncha.It is one of the most troublesome and damaging insects that infest our trees and represents a challenging problem for anyone involved in gardening, whether it be organic or not. However, despite being a resilient parasite, it is still possible to intervene with organic remedies to defend our plants and limit their spread and proliferation.
In this article, we want to present you with some remedies against cochineal and show you the main species present in our territory.
The male and female cochineal
Cochineal is sexually differentiated, and also visually distinguishable between male and female (with some hermaphroditic exceptions). The male has a small elongated body with thin legs and a developed thorax. The female, on the other hand, often has the head and thorax united, lacks wings, and has almost entirely absent legs. Reproduction occurs sexually, but sometimes cases of parthenogenesis can also occur.
Various species of cochineal
There are several species of cochineal in nature, distinguished by the type of tree crops they attack and the damage they cause. Let’s see the main ones.
Cottony cushion scale
One of the most well-known species is the cottony cushion scale, Icerya Purchasi Mask. It belongs to the order Rincoti and the family Monophlebidae.
As the name suggests, the cottony cushion scale mainly attacks citrus trees (but also acacia, broom, and ornamental plants). If not controlled during a severe infestation, it causes the withering and drying of leaves. In the most serious cases, it can lead to the death of the plant.
This species of cochineal is of Australian origin and is mainly present in areas with a temperate climate. It has a reddish-colored body covered with whitish wax. It attacks the underside of citrus leaves, fruit peduncles, and young branches, sucking sap from the plant, which slows down its development. Moreover, it produces abundant honeydew, soiling the vegetation and fruits and leading to the appearance of sooty mold.
Another widespread species in our country that needs to be dealt with is the soft scale, Saissetia oleae Olivier. This insect also belongs to the order Rincoti but the family Dactylopiidae.
This species mainly attacks olive trees, but also citrus trees and ornamental plants. It thrives in mild and temperate climates.
With a brown color tending towards black, the soft scale, during the oviposition phase, causes damage to the branches and leaves through feeding punctures. The insect settles on the underside of leaves, sucking vital sap from the plant, hindering the development of shoots, and causing a lower fruit yield, with the fruits easily falling off.
The affected plants wither, and their branches and leaves dry up. Naturally, fruit production is severely compromised as well.
Like the cottony cushion scale, the “Saissetia oleae” also produces honeydew, which, in addition to suffocating and causing burns on the leaves, attracts ants, which, in turn, stimulate the parasite to produce even more honeydew, further favoring the appearance of sooty mold that worsens the damage.
One last species of cochineal we want to introduce is the cochineal scale, Dactylopius coccus.
This type of insect is known mainly for its properties rather than the damage it causes. Its body and eggs are used to extract carmine acid to produce carmine, a natural dye widely used in the food industry as food coloring E120 or E124. It is also used in cosmetics to produce lipstick. It should be noted that carminic acid can now be synthetically produced using modified bacteria for this purpose.
However, the cochineal scale is still classified as a parasite. It develops on cacti of the genus Opuntia (the well-known prickly pear cactus, for example). Therefore, if your purpose is to grow and harvest prickly pears and not produce carmine, then you should take action immediately when you notice the presence of this insect. Also, if you follow a vegan diet, be cautious about colorants. They can be found in many red-colored foods such as candies, beverages, syrups, and ice creams.
While it is a natural dye, it is still of animal origin. Finally, it should be noted that the ingestion of this dye appears to have a negative impact on children’s hyperactivity.
Remedies against cochineal
Remedies against cochineal are not always easy to apply. Protecting plants from attacks by this parasite is not simple at all. Each of the different species we have seen possesses natural defenses that hinder the action of predatory insects.
The production of honeydew and sooty mold also attracts other insects like ants, which further promote the parasite’s proliferation.
Some species, like the cottony cushion scale, produce waxy substances that limit the action of natural preparations such as nettle macerate and garlic macerate. Even the use of chemical insecticides, which we strongly discourage, is ineffective against this parasite. Moreover, it causes significant damage and increases the insect’s resistance.
Now, let’s see the most effective organic remedies against cochineal.
Most gardeners recommend using white oil to eliminate cochineal. It is a mineral oil derived from the fractional distillation of crude oil. In agriculture, it is used as an insecticide. The refining process removes the toxic substances present, which is why its use, under certain conditions, is allowed in organic farming.
White oil can be applied only on fruit trees during winter when the plants are in a state of vegetative rest and the temperatures are very low but not below freezing. It should not be used when there is snow or precipitation, as it would be ineffective.
For those who choose this remedy, we advise strictly following the instructions on the product label (product available here).
However, keep in mind that the use of white oil is allowed in organic farming, but it is still a product derived from the processing of petroleum, so not entirely ecological! From our perspective, if possible, we recommend choosing other types of remedies.
Potassium soft soap and pure Marseille soap
The use of pure Marseille soap and potassium soft soap as insecticides for organic gardening can be a valid alternative. Actually, these products have various uses, as we have already discussed previously. Here, we specifically mention their effectiveness against cochineal. They can also be used in warm weather when cochineal proliferates and causes the most damage. They act on contact, causing the insect’s pores to clog, leading to its suffocation. Additionally, they wash the plant from honeydew and sooty mold.
To improve the action of soap, you can proceed by first cleaning the cochineal present on the plant. You can use a brush with soft bristles (or cotton swabs) and a solution of water and soap.
You can find pure Marseille soap here and potassium soft soap in a specific formulation for agriculture here.
Another effective active ingredient against cochineal, which can be used in all seasons, is neem oil in its simple formulation (available here) or azadirachtin in specific formulations for agriculture. To enhance the action of neem oil, you can mix it with pure Marseille soap. This way, you achieve a dual effect.
Among natural macerates, the most effective against cochineal is the fern macerate. This macerate can be used undiluted in winter or diluted in 10 liters of water during spring and summer. In this case, it is best to first clean the plant infested with cochineal and then apply the macerate during the cooler hours of the day. Its repellent action prevents the reappearance of the parasite. It can be used in combination with one of the remedies mentioned earlier.
You can find a ready-to-use product here.