Aphids, also known as aphids, are one of the most common pests affecting plants in gardens, orchards and cash crops around the world. Despite their small size, these insects can wreak havoc on our plants, decreasing their health and performance if not properly controlled. In this article, we will explore all aspects related to aphids: from their anatomy and life cycle to their impacts on plants and the most effective control strategies.
# # # How do aphids feed on plants? # # #
Aphids feed on plant sap, making them sucking insects. This feeding process can be described as follows:
Sting: The aphid uses its mouthparts to pierce the plant and reach the vascular tissues that contain the sap. Its mouthparts consist of a long, pointed oral stylet, which can be penetrating or sucking, depending on the species of aphid.
Sap Extraction: Once it has entered the plant, the aphid begins to suck sap from the tissues. The sap is rich in nutrients, mainly carbohydrates, essential for the survival and reproduction of aphids.
Honeydew production: As a result of their diet, aphids excrete a sweet liquid called honeydew. Molasses is a byproduct of sap digestion and is high in sugars. This sticky liquid is excreted by the aphid in large quantities and can accumulate on the leaves and stems of host plants, attracting the appearance of other insects or fungi such as sooty mold (this layer which resembles black ash).
# # # Aphid anatomy and life cycle # # #
Aphids are small insects, usually green or black, although their color can vary depending on species and environmental conditions. They typically measure between 1 and 3 millimeters in length, making them almost microscopic creatures to the naked eye. Their soft bodies are covered in a waxy cuticle that provides protection against dehydration and predators.
The aphid life cycle includes several stages: egg, nymph and adult. Eggs are laid by females on plants in late fall or early winter. These eggs hatch in the spring, giving way to nymphs, which are smaller versions of the adults. The nymphs actively feed on plant sap and undergo several molts before reaching sexual maturity. Adults are able to reproduce quickly through parthenogenesis, a process in which females produce offspring without the need to mate. This accelerated reproductive cycle is one reason why aphids can quickly increase their populations and become devastating pests.
Under certain conditions, such as overpopulation or environmental changes, some nymphs may develop wings. These wings allow them to disperse to new plants and colonize uninfested areas.
# # # Types of aphids: How to identify them? # # #
There are a large number of species of aphids but they are generally identified by their shape, color and host. The main aphids that can be found on our plants are:
-Black bean aphid (Aphis fabae). It has a small black body and white and blackish legs. It is very common for it to attack beans, although it can also affect many other types of plants.
-Apple aphid (Aphis pomi). This aphid is green in color and has a recognizable pear-shaped body. Although its favorite host plant is the apple tree, it is also found in the pear tree, the European loquat, the quince or the rose bushes.
-Cotton aphid (Aphis gossypii). The cotton aphid is small, about two millimeters long, and has a rounded yellowish or dark green body. It is common in cotton plants; although it can also affect many other horticultural plants such as watermelon, cucumber, melon, pumpkin or citrus fruits.
-Oleander aphid (Aphis nerii). This type of aphid has a striking yellow-orange color. In addition to feeding on oleanders, this type of aphid also causes damage to dipladenia, plumeria or vincas. It is sometimes also found in citrus fruits, euphorbias, bellflowers and asteraceae.
-Cabbage aphid (Brevicoryne brassicae). Its body is grayish green. It is very recognizable because it is usually covered in a waxy secretion that makes it appear whitish at first glance. This aphid feeds only on plants in the Brassicaceae family (cabbage, cauliflower, broccoli or radishes, among others).
-Apple aphid (Dysaphis plantaginea). Its body is blue-gray covered with a powdery wax. The apple tree is its main host; although it can also be found in plants of the Plantago genus.
-Green citrus aphid (Aphis spiraecola). It has a rounded green body with black legs. It is doubly dangerous for its host plants because, in addition to feeding on them, it can also transmit different viruses; Most worrisome is what is commonly known as “citrus sadness virus,” which can lead to the death of any affected trees and plants. In addition to citrus fruits, this type of aphid also likes rose bushes, peach trees, pear trees, almond trees, medlar trees, apricot trees and other rose bushes.
-Mealy plum aphid (Hyalopterus pruni). Pale green or brown in color covered with a white waxy powder. It originates from Europe and measures between two and three millimeters. In addition to the plum tree, its main host, this type of aphid also attacks the rest of the plants of the Prunus genus.
# # # How to detect the presence of aphids on plants? # # #
Symptoms caused by aphids on plants can vary depending on factors such as the species of aphid, the host plant, and the severity of the infestation. However, there are several common symptoms that we can observe in our plants to identify the presence of aphids:
Leaf deformation: One of the most visible symptoms of an aphid infestation is the deformation of plant leaves. This may manifest as leaf curling, edge curling, or blistering.
Yellowing Leaves: Leaves infested with aphids often show signs of yellowing, especially in areas where the insects are actively feeding. This yellowing may be caused by a loss of nutrients due to sap sucking by aphids.
Delayed Growth: Plants infested with aphids may experience a delay in their normal growth and development. This is due to decreased photosynthesis and nutrient absorption caused by aphid feeding, which negatively affects plant performance.
Formation of sticky leaves: Aphids excrete a sticky substance called honeydew, rich in carbohydrates, while feeding on plant sap. This honeydew can coat leaves and other nearby surfaces, making them sticky to the touch. The presence of honeydew can also attract the formation of fungi such as black mold, sooty mold, which further aggravates the plant's problems.
Presence of ants: Ants maintain a symbiotic relationship with aphids, since they feed on the honeydew they secrete. Therefore, the presence of large numbers of ants on a plant may be a sign of an aphid infestation nearby.
Disease Transmission: Aphids can transmit disease-causing organisms, especially viruses. Viruses are transmitted mainly by winged individuals. One such example is Potato Virus Y (PVY), which is transmitted by aphids on tomatoes, as is Cucumber Mosaic Virus (CMV) on cucumbers, or Citrus Sadness Virus.
These are just some of the most common symptoms that can indicate the presence of aphids on plants. It is important to monitor plants regularly for early signs of infestation and take preventative or control measures as necessary to protect plant health and performance.
# # # The association between ants and aphids: how does it work? # # #
In this symbiotic relationship, the ants act as protectors or "breeders" for the aphids, while the aphids provide a valuable food resource for the ants. This mutualistic behavior has been the subject of study and fascination by scientists for decades.
Ant protection: Ants actively protect aphids from predators and parasites. Ants defend aphids from other predatory insects, such as ladybugs, and may even attack other ants that try to prey on aphid colonies. This protection is due to the fact that the ants feed on the honeydew that aphids produce by feeding on plant sap.
Aphid Feeding and Care: For their part, aphids feed on plant sap and produce honeydew as a byproduct of this process. Ants, in turn, consume this honeydew as a source of carbohydrate-rich nutrition. Furthermore, aphids can also excrete honey droplets directly into the pound cake, reinforcing this interdependent relationship.
# # # Aphid Control Strategies: How to Fight Them? # # #
Given the potential damage that aphids can cause, it is crucial to implement effective control strategies to combat these pests. This pest can be fought both naturally and through the use of insecticides. However, it is essential to act early to reduce the impact they can have on our crops.
1. Chemical control
Chemical insecticides can also be used to control aphid populations, but care must be taken to avoid harming natural enemies and to minimize environmental impacts. It is recommended to use selective insecticides and carefully follow label instructions.
Some of the treatments are:
RAPE OIL (domestic use)
PYRETHRINS (domestic use)
DELTAMETRIN 2.5% (domestic use)
FLUPIRADIFURONE 1.88% (professional use)
2. Physical control
Other options include using physical methods, such as applying pressurized water to kill aphids on plants or using sticky traps to monitor and capture the insects.
We leave you the link to create your own sticky traps:
How to create your own traps3. Biological control
One of the most effective and long-lasting ways to control aphids is to use their natural enemies, such as ladybugs, parasitoid wasps and hoverfly larvae. These predators actively feed on aphids and can help control their populations naturally.
Let's talk a little about each of these predators:
Adonia variegata (Catarina or San Antonio seven-pointed cow). It is a species of orange-red ladybug with seven black spots on its elytra. Like other ladybugs, Adonia variegata is a predator of aphids. It feeds on adult aphids and its larvae can also consume large quantities.
Aphidoletes aphidimyza. It is a small black fly with transparent wings. The larvae of Aphidoletes aphidimyza are parasitoids of aphids. They feed on aphids by entering their bodies and consuming them from the inside.
Chrysoperla carnea (Lacewing). They are light green insects and have large compound eyes. Its wings are transparent and very veined. Lacewing larvae are voracious predators of aphids. They consume large quantities of aphids during their larval development.
Coccinella septempunctata (Seven-spotted ladybug). It is an orange-red ladybug with seven black spots on its elytra. This species of ladybug feeds on aphids at all stages of their life, both as larvae and as adults.
Episyrphus balteatus (Hyrphid fly). It is a fly that resembles a bee, with yellow and black stripes on its abdomen. The larvae of Episyrphus balteatus are predators of aphids. They feed on large quantities of aphids during their larval development.
Eupeodes corollae (Hyrphid fly). Similar to Episyrphus balteatus, it is a bee-mimic fly with yellow and black stripes on its abdomen. The larvae of this fly also feed on aphids, helping to control their populations.
Lisyphlebus testaceipe. It is a small brown or yellow wasp. Lisyphlebus testaceipes is a parasitoid of aphids. It lays its eggs inside the aphids, which eventually causes the aphid to die, leaving what are called mummies.
Propylea 14-punctata (Fourteen-spotted ladybug). It is an orange-red ladybug with fourteen black spots on its elytra. This ladybug feeds on aphids at all stages of their life.
Scymnus spp. (Ladybugs). Various species of ladybugs which can vary in color and number of spots on their elytra. Ladybugs of the genus Scymnus are predators of aphids and feed on them at all stages of their life.
You know, if you see one of these insects in your garden, don't kill it, leave it alone and it will do the dirty work
How to attract natural predators?
Attracting natural aphid predators to our garden or crop can be an effective and environmentally friendly strategy for naturally controlling aphid populations. Here are some ways to attract and encourage the presence of these beneficial predators:
1. Plant Attractive Plants: Some plants, such as river alder (Alnus glutinosa), cilantro (Coriandrum sativum), and oats (Avena sativa), are known to attract beneficial insects, including aphid predators. Incorporating these plants into our garden can provide shelter and food for predators, increasing their presence.
2. Create favorable habitats: Provide additional shelter for natural predators by creating suitable habitats. This can include installing insect hotels, woodpiles, dense bushes and areas of native vegetation, which serve as shelter for predators as well as a food source.
3. Avoid using broad-spectrum pesticides: Chemical pesticides can be harmful to natural predators because they can kill not only aphids but also beneficial predatory insects. Instead, opt for less toxic pest control methods, such as biological control and the use of selective, natural pesticides.
4. Diversify vegetation: Growing a variety of plants in our garden can attract and maintain a diversity of beneficial insects, including aphid predators. Different plant species will provide different sources of food and shelter for predators, increasing their presence and activity.
Aphids are small but powerful insects that can wreak havoc on plants if not properly controlled. Their rapid life cycle and ability to transmit diseases to plants make them a serious threat to global agriculture and horticulture. However, by combining biological, cultural, chemical and physical approaches, it is possible to effectively manage aphid populations and protect plant health and performance. By better understanding the biology and behavior of these insects, proactive steps can be taken to prevent and control aphid infestations, thereby promoting a healthier, more sustainable environment for plants and the environment in general.
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