Today we will talk about an insect that is very harmful to our vegetable garden and annoying to our homes: the bugs. In particular, we will focus on the green bugs and the Asian bugs (also known as Chinese bugs). These are the two most common species in our territory, capable of causing truly harmful infestations.
These insects, especially during hot periods when they are always in search of food, seriously endanger our crops, often ruining a significant part of the harvest.
Therefore, it is essential to quickly learn how to recognize the different stages of development of green and Chinese bugs present in our soil. This way, it becomes possible to understand how to avoid infestations in advance. Consequently, we can defend our crops in an organic way without the use of pesticides.
Among the different species of bugs, the most widespread and well-known are the green bugs, Nezara Viridula. They are insects of the order Hemiptera, suborder Heteroptera, and family Pentatomidae.
The adult green bugs have a typical bright green color, which can vary to greenish-yellow, pentagonal shape, and can reach a size of about 15 mm. Green bugs reproduce through intense oviposition activity, releasing eggs in compact groups of a light color.
Pay attention to the nymphs, which are the young stages. As seen in the photo below, they have a different appearance from the adult insects.
The nymphs, equally harmful as the adults, are black with white punctuations both at the center and in particular longitudinal rows at the edges of the body. Unlike adult green bugs that often act alone, the small black nymphs move and cause damage in groups. They often feast on our plants in more or less extensive groups and are very annoying even just to look at.
Life cycle of green stink bugs.
After the overwintering period of the cold months, the green bugs restart their reproductive cycle in spring. After mating, oviposition activity is intense. This cycle is continuous, allowing for the presence of nymphs, nymphs (intermediate stages), and adults in our gardens at the same time.
For this reason, there can be multiple generations of green bugs in a year. In our country and with our climatic conditions, there are usually two.
Characteristics of green stink bugs
The green bug is a phytophagous insect, meaning it feeds through its mouthparts, either by sucking the sap and internal fluids of the plant or fruit or by removing portions of the plant itself.
It is also a polyphagous insect, meaning it feeds on an indefinite number of plant species, not just one type of plant (a characteristic of monophagous insects, such as the olive fly).
Damages to Crops by Green Bugs
The phytophagous activity of green bugs is carried out through feeding punctures. The plant species most affected by the polyphagous activity of green bugs are: solanaceous crops (tomato, pepper, eggplant); legumes; some herbaceous crops in open fields (such as chard and basil); some tree crops (such as hazelnut).
Damages to crops are caused by both nymphs and adults. In particular, on tomatoes, feeding punctures cause typical chlorotic punctures of variable extension.
This damage is more frequent on fruits in the ripening phase, as they are easier for the bugs to attack.
Subsequently, the punctures extend and become real necrosis, although very faint.
Another direct damage caused by green bugs on tomatoes, and generally on fruits, is the imparting of an unpleasant taste. A bitter and acidic taste at the same time, making the tomato fruit inedible. This occurs following the puncture, through the secretion of a repugnant liquid.
In addition to the direct damages, plants affected by green bugs are more susceptible to other diseases, such as bacterial infections. These diseases find an easy foothold through the wounds that the insect causes.
Finally, how can we forget the foul odor and unpleasant sensation that green bugs produce when they are crushed.
Asian (or Chinese) Bug
Unfortunately, the green bug is not the only bug present in existence today today. A new species, in fact, is emerging in our vegetable gardens: the dreaded Asian bug, Halyomorpha halys.
This type of bug is, in fact, of Asian origin. It arrived in the United States at the end of the 1990s and appeared in Europe at the end of the last decade. It was first found in the province of Modena in 2012. From there, it began to spread throughout the national territory, becoming known as the Chinese bug.
The Asian bugs have similar characteristics to green bugs. They differ from the latter mainly in color, which is marbled brown. In addition to the typical chromatic pattern, you can also notice a particular detail in the final part of the body, a triangle of darker color.
Just like green bug nymphs, Asian bug nymphs also tend to group together. The biological cycle of the Asian bug (which belongs to the same entomological category as Nezara Viridula) can be assimilated to that of green bugs.
Damage to Crops and Risk to Houses by the Asian Bug
The alert and interest in the Asian bug arise after the damages recorded on some American crops. While in Asian countries of origin, the insect is considered an occasional pest of soy and some fruit trees, in the United States, it has attacked over 300 species of fruit trees, vegetables, and ornamental plants!
The attacks have already been registered on fruit trees such as: apricot, cherry, fig, kiwi, apple, pomegranate, hazelnut, walnut, pear, peach, plum, and olive.
Among the damaged crops, we couldn’t miss the tomato, bean, chili pepper, pumpkin, etc.
Just like green bugs, Asian bugs also cause damage through feeding punctures, and they do so at any stage of development. In the photo, for example, we can see the damage caused by an Asian bug in the nymph stage (intermediate between the nymph and the adult stage). Also, in the photo, we observe a different coloration, black, of the insect not yet adult.
Another danger recorded in the United States, which raises great concern, is the tendency of these bug species to hibernate in the nooks of houses neighboring the crops. This happens with a mass migration of thousands of specimens.
For further insights on the subject, you can find them here.
As in the case of the tomato leaf miner (recently arrived from South America), we wonder how sensible it is to carry out international trade for vegetable products that can also be grown locally. The economic interest to be safeguarded does not seem to be that of the farmers, whose products are devalued to make way for intercontinental exports. In fact, for this type of commerce, the greater profit goes to large distribution companies that manage it.
Certainly, consumers do not benefit, as they find poorly controlled products on their tables.
With even more certainty, we can say that local ecosystems do not benefit, as they are unfortunately invaded by destructive insects they are not prepared for. The same green bug, which we are all accustomed to, actually has an exotic origin, specifically South American.
Having recognized the perverse mechanism of international distribution in the fruit and vegetable sector, the message we want to convey is to consume healthy and consume locally! The invitation we extend to our readers is to boycott, as consumers primarily, productions coming from transnational markets. By buying a South American tomato, we are not supporting a small producer from South America, but rather a huge distribution chain that exploits local producers and alters not only the ecosystem but also the correct economic dynamics.
That said, we can now move on to the biological defense against the bugs present in our vegetable garden.
Biological Defense against Bugs in Our Vegetable Garden
Let’s begin the last part of our article on Asian and green bugs with a consideration. Agricultural manuals indicate chemical control as the main method for eliminating these insects. However, this type of strategy has proven to be a complete failure over time, causing more harm than benefit.
As is often the case with some insect species (such as the potato beetle), treating them chemically has led to increased aggressiveness and resistance. Some species, in fact, have great abilities for adaptation and absorption of the different treatments they are subjected to. This often triggers a vicious cycle that forces farmers to use increasingly powerful, numerous, and toxic active substances for the entire ecosystem.
Therefore, let’s see how it is possible to implement biological defense, bearing in mind that bugs are tough insects to kill, highly prolific, and resistant.
Water and Pure Marseille Soap or Potassium Soap
After all this preamble, recommending water and soap to eliminate green and Asian bugs from the vegetable garden might seem misleading. But it’s not, and we understand why.
Bugs use subcutaneous pores to breathe, or rather, under their outer shell. If the water and soap solution reaches those pores and blocks them through desiccation, the bug dies. Of course, it is necessary to use a specific, pure soap. Marseille soap is a remedy allowed in organic farming.
Its effectiveness, in this case, depends on the difficulty in application and the physical structure of the bugs themselves.
In general, it is difficult to target all parts of the plant affected by the infestation with any solution. Both green bugs and Asian bugs have the habit of hiding under the leaves. Therefore, pay attention to the lower side, which must be thoroughly wetted.
If there is no direct contact on the pores, the solution cannot take effect. The solution of water and pure Marseille soap has a better chance of success if the bugs are in the nymph stage. In the adult stage, the hard shell partially acts as an umbrella and makes the treatment slightly less effective.
As for the type of soap to use, we recommend pure Marseille soap or potassium soft soap. The former can be purchased here. The latter can be found here.
Among the agronomic defense techniques tested by farmers against bugs, one of the most effective is the use of anti-insect nets. These are particularly useful for protecting fruit trees such as peaches, pears, kiwis, etc., from the attack of Asian bugs. The anti-insect net has proven to be an effective barrier to reduce damage caused by adult insects’ feeding. For very extensive orchards, this solution can be costly and challenging to apply. However, in a domestic setting, to protect a few trees during peak infestations, it is a safe solution that we recommend adopting. You can find good anti-insect nets here.
Especially in the nymph or hibernating stage, both green and Asian bugs tend to gather in groups. When we see these clear signs while walking among the tomato rows, we should pinch our noses and take the opportunity for a manual removal of the nymphs. Once collected, they can be drowned in a bucket with water and soap for final disposal.
Natural Attraction with Sacrifice Plants
As we saw in the introduction on green bugs, these insects are highly attracted to various types of plants. They love tomatoes, but there are other plants that attract them even more. Let’s exploit this weakness by sowing sacrificial plants on the edges of the vegetable garden. This way, we will be alerted in time to the presence of bugs and catch a good number of them. Basil is an excellent example for this purpose.
It doesn’t cost much space to sow a few extra basil plants in strategic areas. This way, we can monitor the situation and easily collect the bugs since we know where they will go in search of food. Another plant that is highly favored by this type of insect is yellow mustard.
Identification and Destruction of Winter Nests
These dreaded pests, whether green or Asian bugs, will seek a place to hibernate after their summer feasting. As we have seen when talking about Asian bugs, this has been a significant problem in the USA. Wooden houses, in particular, are fantastic natural shelters for bugs like these.
In late autumn or in the middle of winter, we need to search the surroundings of our vegetable garden to understand where the bugs might have built their nests and locate them. Wood, large stones, cement cracks, and perforated bricks can all be ideal hiding places to start our search.
Once the nest is identified, it should be destroyed. Where allowed by the changes made to Legislative Decree 152 of April 3, 2006, in our opinion, fire is the best solution. However, extreme caution must be exercised!
Naturally, using fire is not an option if the bug nest is found inside the house. In such cases, we recommend courage and a good dose of luck. Many people suggest using old clothes or sheets, preferably flannel, to place in strategic locations or an old cellar. Bugs are attracted to the fabric and will get trapped in it. Then, it will be easier to gather the cloth with the bugs inside and get rid of them.
Another approach we recommend to keep bugs away from the vegetable garden is to use natural macerations and preparations. We are referring to nettle maceration, garlic infusion, and tomato leaf maceration, which we discussed earlier. In this case, the action is repellent and preventive. Direct contact has little effect on elimination, but it may encourage bugs to change their location.
We want to inform you about some updates in the biological fight against the Asian bug, specifically regarding the identification of its insect predator. For more updates, you can read them here.
- Green Stink Bug – Chinavia halaris (Say) from University of Florida: This resource discusses the green stink bug, Chinavia halaris, which is a commonly encountered pest of seeds, grain, nuts, and fruit in both the nymph and adult stages across North America.
- Southern Green Stink Bug – Nezara viridula (Linnaeus) from University of Florida: This resource provides information about the southern green stink bug, Nezara viridula, a highly polyphagous feeder that attacks many important food crops.
- Stink Bugs on the Move from Iowa State University: This resource discusses the movement of stink bugs, including green stink bug nymphs, which are black with bright green and yellow or red markings. Adults are light green, shield-shaped, and have fully developed wings.
- Insects: Japanese Beetle and Stink Bug from University of Nebraska-Lincoln: This resource provides information about green stink bugs and Japanese beetles. Adults are bright green and measure ½ to ¾ inch long.
- Stinkbugs (Family Pentatomidae) from University of Wisconsin-Milwaukee: This resource discusses stinkbugs, including green stink bugs that drink the juice from a wide variety of leaves, flowers, and fruits.