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Fig Scale: Understanding the Threat, Inflicted Damage, and Organic Defense Strategies

Understanding and Combating the Fig Scale Insect. Learn about the most worrisome parasite affecting fig trees and other fruit-bearing plants, and discover effective organic defense strategies.

by BioGrow

The figs wax scale is a scale insect also called fig scale, and it is the most concerning parasite for the cultivation of this fruit tree. This holds true both in domestic settings and specialized orchards. We’ve already discussed the most common species of scale insects. Today, we want to dedicate a special focus to this fig parasite, whose presence has increased in orchards in recent years, leading to a rise in related damages.

Let’s delve into the characteristics of the figs scale insect, the damages it causes to trees, and effective methods for organic defense.

Identifying the Fig Scale Insect

The figs scale insect, scientifically known as Ceroplastes rusci, is an insect of the order Hemiptera, superfamily Coccoidea, family Coccidae. This species particularly attacks the fig tree, but it is actually a polyphagous species, meaning it can affect other important crops. Some of these include: mulberry, blueberry, lemon, oranges, and citrus in general, laurel, vines, strawberry tree, holly, olive tree. Additionally, it can also affect trees and shrubs like oleander, mastic tree, poplar, and plane tree. It is native to the East but is now widespread throughout the Mediterranean basin. In Italy, it is present across the territory, especially in the coastal areas of southern regions and on the islands.

Description

Adult female fig mealybug

Adult female fig mealybug

The adult figs scale insect differs significantly by gender. Adult females appear as tiny turtles, semi-oval in shape, about 4 mm long and wide. They are grayish with reddish shades. The outer part is a kind of wax shield, consisting of a larger central plate and eight side plates. The lower part of the body is soft, with a reddish belly, which adheres to the vegetation. The figs scale insect is equipped with a rostrum with a needle-like capillary tube, through which it sucks sap from plants. The adult male is different. It is a small iron-colored insect, just over 1 mm long, with two antennae, two wings, six legs, and two long wax cylinders at the rear. The newly hatched larvae are the same for both male and female. They have an elongated and elliptical shape, well-developed antennae and legs, and a tawny color. When the larvae attach to vegetation for feeding, they begin to develop the wax shield and differentiate sexually.

Life Cycle of the Fig Scale Insect

Normally, the figs scale insect completes one generation per year, but in recent years, especially in southern regions, it has been observed to have two generations. Females overwinter as third-instar nymphs or adults, resuming their activity in April. Egg laying begins in May, with 800-1500 eggs produced by each individual. After 15 days, the new larvae hatch, starting to invade the vegetation of the fig tree. If the infestation is high, clusters or small groups can form, which can easily fall to the ground with the wind. This contributes to the parasite’s proliferation and infestation of healthy plants. In August, adult males appear, dying immediately after mating. Females continue to grow and then overwinter in place, especially on the underside of branches, where they are more covered. The potential second generation begins in July-August.

Damages to Figs and Other Plants

Fig scale insect
Damages from the figs scale insect can be severe, depending on the extent of infestation. The parts of the plant affected are mainly the branches, but also the leaves and fruits. As mentioned, the scale insect, with its strong rostrum, sucks the plant’s juices, depriving it of nutrients. Another direct damage is the emission of a sugary substance, forming a layer of honeydew. This, in turn, initiates the presence of sooty mold, and the honeydew attracts other parasitic insects, especially ants. Sooty mold is that annoying black patina. In case of severe attacks, it leads to the decline of the plant, as it hinders the free exchange of gases, interrupting formative processes. As a consequence of all this, there is a delayed and incomplete maturation of the fruits, or their withering in the case of excessive proliferation in late summer. The few fruits that manage to survive have poor quality and, being soiled, are unappetizing. In the years following the first attack, the situation for the tree can worsen. There will be, indeed, poor flowering, and in more severe cases, the death of the plant may occur.

Organic Defense against Fig Scale

Natural Antagonists

Fig scale is a highly challenging parasite to combat. In nature, some natural antagonists would be present, but the indiscriminate use of pesticides in recent decades has reduced their presence. Decreased natural antagonists, of course, translate to increased resistance and easier proliferation of the species. In any case, the main natural antagonists of fig scale are:

  • Some predators, Lady Beetles, for example, Chilocorus, and Exochomus;
  • Some parasitoid wasps, such as Scutellista cyanea and Tetrastichus ceroplastophilus.

Manual Removal

Where the presence of natural antagonists is not sufficient to reduce the fig scale population, intervention is necessary. A good artisanal method to eliminate this parasite is manual removal from trees. This can be easily done where the tree is young or grown with low branches. Manual removal should be done in the winter when the larvae, still visible, are overwintering. Technically, for removal, you can use an old clothes brush or a strong pair of leather gloves (like these). Reinforced fabric can also be useful. In any case, before manual removal, it is advisable to provide a biological treatment, let’s see which ones to choose.

White Oil

In general, to eradicate various species of scale, the use of mineral white oil is recommended. It is a product whose use is permitted in organic farming. You can find it here. Mineral white oil is applied in winter when plants are in a state of vegetative rest. Temperatures should be low but preferably above freezing. For specific use, the advice is to follow the instructions on the product label. A few days after applying the white oil, it is easier to proceed with manual cleaning.

Potassium Soap

We have already talked about the use of potassium soap as natural insecticides. Also, for fig scale, this remedy is effective.
Potassium soap acts on contact, causing the closure of the pores on the upper part of the insect. This leads to death by asphyxiation. After using the soap, it is much easier to proceed with plant cleaning, as mentioned earlier. Another advantage of using potassium soap is that it also cleans the sooty mold that the fig scale creates on vegetation. Moreover, it can be used in spring when infestations resume. You can find a great organic potassium soap here.

Proper Pruning

We have already described the fig pruning techniques. In the fight against fig scale, pruning can be a necessary intervention for severe infestations. The fig is a very robust and resistant plant that recovers well even after drastic interventions.
The removal of infested branches can make plant care more manageable. The important thing is to completely eliminate infested branches and vegetation, proceeding with their burning. We recommend this type of intervention in February/March.

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