Green shield bugs are very damaging parasites for the plants in our organic garden. They are present throughout our territory, from North to South, and their infestations can be truly detrimental. Especially during hot periods, when they are always in search of food, they seriously endanger our crops, often ruining a significant portion of the harvest.
In this article, after a detailed description of the parasite, we will see how to eliminate Green shield bugs and remedy infestations in an organic way. Furthermore, we will explore the damages that the insect causes to crops.
What are Green shield bugs
The green shield bug (Palomena prasina Linnaeus, 1761) is a European bug species in the family Pentatomidae. The species Palomena prasina should not be confused with the Green shield bugs and asian stink bug, similar insects but with different characteristics, nor with the bed bug or the cabbage bug.
- The adult of Green shield bug has a typical bright green color, which can vary towards green-yellow.
- It also has a pentagonal shape.
- It can reach sizes of about 15 mm.
- It reproduces by laying eggs in compact groups of light color.
Nymphs are Green shield bugs in the juvenile stage. They look different from adult insects. They are black in color, with white spots both in the center and in specific longitudinal lines on the edges of the body. And, above all, they are as harmful as the adults. Unlike the adults, which often act alone, the small black nymphs move and cause damage together.
Characteristics of Green shield bugs
Green shield bugs overwinter in cold months and resume reproduction in spring. The egg-laying activity is intense, and the cycle is continuous. Due to this characteristic, it is not uncommon to find both nymphs and adults in our gardens. For this reason, there can be multiple generations of Green shield bugs in a year. In our country and under our climatic conditions, there are usually two generations. It is a polyphagous insect, damaging an indefinite number of plant species. It feeds through its mouthparts and does so in two ways:
- Sucking plant sap and internal fluids from the plant or fruit;
- By removing portions of the plant itself.
Which Plants are Attacked by Green shield bugs
The plants most affected by the polyphagous activity of green shield bugs are:
- Solanaceae like eggplant, tomato, and bell pepper;
- Leguminous plants;
- Other herbaceous crops in open fields like Swiss chard or basil, hemp;
- Some tree crops like the hazelnut.
What Damages Green-shield-bugs Cause to Plants
The damages to plants are caused by both nymphs and adult green bugs. The preferred plant of the Palomena prasina is undoubtedly the tomato, especially ripe fruits. The feeding punctures on these vegetables cause typical chlorotic spots and inject a repugnant liquid into the fruit. When these spots spread, they become necrosis. The taste also becomes very unpleasant, bitter and acidic at the same time, rendering the tomato inedible. Additionally, the odor of the fruit becomes bad. Plants affected by Green shield bugs also tend to get sick more. They are particularly prone to bacterial infections and other diseases.
Here’s How to Eliminate Palomena prasina from the Garden
Green shield bugs are very difficult insects to eliminate. They are resistant to chemical pesticides as well; in fact, their intensive use has increased their resistance. Getting rid of green bugs is therefore a truly challenging task, putting farmers’ patience to the test. After so much effort, we could still find all the fruits ruined by real invasions. There are several methods to eliminate these insects:
- Manual removal,
- Trap plants,
- Potassium soft soap,
- Natural pyrethrum.
All these methods are valid depending on the intensity of the infestation in the field.
Manual Removal of green bugs from Plants
In the home garden, the first defense strategy against Green shield bugs is manual removal. As we have seen in the descriptive part of this article, this parasite moves in groups at the nymph stage. So, this is the best time to catch and eliminate them. Once the insect becomes an adult, it moves around the plants more sporadically; furthermore, it can fly and move quickly, making manual removal difficult. Therefore, the first rule is to act on the nymphs. To find them, look under the leaves of your plants; that’s where they often hide. Be sure to spot small groups of black insects, then remove the entire leaf. At this point, they can be squashed on the ground or soaked in water and soap to drown. Of course, this type of strategy is feasible for a small number of plants. It’s impractical for extensive fields.
Use of Trap Plants
Beyond tomatoes, Green shield bugs are strongly attracted to various types of plants. One method to eliminate them is to exploit this weakness to our advantage. To do this, simply sow sentinel plants at the edges of the garden, so you can be alerted to their presence in advance and capture a good number of them. A good example for this purpose is basil: the plants take up little space, and sowing them in strategic areas of the field allows you to monitor the situation. Knowing where they will search for food, you can easily collect the Palomena prasina. Another plant that this insect like a lot is yellow mustard.
Potassium Soft Soap
A more direct natural remedy to eliminate Green shield bugs from the garden is the use of potassium soft soap. For effectiveness, this organic remedy should be used when the insect is in its juvenile stages, the aforementioned nymphs. The armor of young green bugs is not too thick and can be easily clogged by soap. The soap, when deposited on the insect’s body, dries it out. So, direct and thorough application of the solution is important. We recommend a soap specifically for agriculture.
Among products allowed in organic farming, natural pyrethrum is effective for eliminating Palomena prasina. Here too, the same advice as for soft soap applies: try to target the Green shield bugs when they are still small and moving in groups. Hitting isolated adult insects is very challenging and risks wasting a lot of product. Here you can find many pyrethrum-based products. To use them correctly, follow the instructions on the label.