Gardening

Aphids: Complete Guide to Aphids on Plants

The months of May and June are always accompanied by surprises in the garden, among them our friends the aphids . However, what exactly do we know about them? Do they develop all the time in the same plant? Do they change color? How long do they usually live? How can we control them? Next, we will try to answer all those questions about aphid pests on garden and orchard plants.

APRIDS ON PLANTS

They may always seem the same to us, but there are more than 900 species in Europe and some 4700 species worldwide!

Damage of aphids on plants

Aphids feed on the sap of plant phloem (that is, a liquid rich in sugars) using their biting-sucking mouthparts. These bites cause the leaves to curl . On some occasions, aphids can also transmit viruses from one plant to another . The main symptoms that we can observe are yellowing or the appearance of small mosaics on the leaves .

As we have told you in other articles, aphids have small tubes at the end of their bodies called “cornicles” or “siphons” through which they excrete a sugary substance known as “molasses”. Honeydew can, in turn, cause indirect damage to plants since ants, in exchange for protecting aphids (from ladybugs, for example), feed on this substance.

On the other hand, it can also cause the appearance of sooty mold, a harmful fungus for our plants. As a curiosity, I would like to tell you that some bees and wasps can collect molasses and from them, obtain dark and strong honeys.

Each aphid can live between one and two months. During that time they can produce between 40 and 100 offspring! They reproduce sexually (male and female) or parthenogenic (there is no need for males, producing identical organisms).

Aphids with wings or without wings

In addition, according to its biological cycle we can differentiate two types. Monoecious species live all year round on the same type of plant . And dioecious species: they alternate their cycle between 2 types of plants . For example, Metopolophium dirhodum is a species of aphid whose primary host is rose bushes but from May-June it makes a migration to its secondary hosts, which are wheat, barley and corn. Therefore, some individuals have wings and others do not. In this way they can colonize other crops .

If we pay attention in the garden we can see aphids on plants of different colors . Most of the time the color can tell us the type of aphid species. However, at other times, the colors may change depending on the type of diet they have. Therefore, the same species can have several different colors. Here we show you the best known. It is good to know the scientific name of the species because, in this way, if you have more questions, you can access more extensive information with the name in Latin.

GREEN APRONS

  • Myzus persicae. Peach aphid . It affects trees of the genus Prunus . It does not usually cause much direct damage but it transmits viruses.
  • Aphis pomi , present in apple trees causing the leaves to turn yellow. However, the most damaging aphid for the apple tree is a brown aphid ( Dysaphis plantaginea ), which can deform the fruits.
  • Acyrthosiphon pisum . It mainly affects peas and chickpeas . It can also be pink. It is usually located at the ends of the stem and in the organs in formation. They are usually observed before flowering.
  • Machosiphum rosae. Present in the  rose bushes . They can also be red in color and is characterized by having very long siphons, as we see in the photo.

BLACK APRONS

  • Aphis fabae . Bean or bean aphid . Installing early can cause significant losses. Sweet winters and warm springs favor their appearance.
  • Brevicoryne brassicae  present in cabbage . It produces a kind of wax that gives it a grayish appearance. We can usually find them in a group. They can cause deformation, discoloration of the leaves and transmission of viruses. As it does not move much it is less dangerous than other species of aphids.

YELLOW APPLES OR WHITE APPLES

These colors, although they are less common, also exist in the different species of aphids. Of course, we must be careful and not confuse them with other species such as mealybugs or Viteus vitifoliae . This small insect very similar to the aphid is responsible for the transmission of phylloxera on the vine . This disease comes from the southern United States and from 1863 caused a great wine crisis in Europe. It was not until after 30 years that we managed to overcome this crisis by using American rootstocks resistant to this disease.

The yellow strawberry aphid ( Chaetosiphon fragaefolii ) or raspberry ( Aphis idaei ) is also well known .

Finally, to finish the list, I need to name the 3 aphids most present in cereals, which are: Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi .

HOW TO ELIMINATE APRIDS AND PREVENT THEIR APPEARANCE

Despite being a common problem, on many occasions we still do not know how to combat aphids. There are various methods to prevent their appearance or to eliminate them once they have reached our crops. Aphid pests are highly dependent on weather conditions and the presence of other insects that can attack them (natural enemies of aphids).

Prevention methods

There is nothing better than prevention. Therefore, from April-May we must pay special attention to our crops. To facilitate the early observation of aphids, especially to detect the arrival of winged aphids, we can make some homemade traps . The favorite color of aphids is yellow. There are several options for catching aphids and detecting their presence:

  • Take a yellow container and fill it with soap and water. In this way the aphids will be attracted to the color and will drown.
  • Cut out pieces (approximately 20 cm) of yellow cardboard and apply oil or rat glue to them. Once prepared we hang them with threads in our garden.

We can also prepare slurry or maceration of nettles and spray it on the plants as an insect repellent, in addition to promoting their immune system. Approximately 100 grams of nettle per liter of water is recommended. It is also recommended to eliminate weeds and place our crops near aromatic plants that are usually repellent against aphids.

Chemical control against aphids

We always have to try to use insecticides as little as possible and carry out integrated pest protection . Therefore, if we decide to use insecticides, it is better to do it soon when we see the first colonies of aphids and before the natural enemies arrive. In addition, the treatment thresholds (minimum number of aphids per plant) must be respected before applying the product. As many aphids hide under the leaves, the use of systemic insecticides is usually the most effective (they are the insecticides that, when applied, penetrate the interior of the plant through the tissues and, from there, are distributed to all parts ). However, you should always pay special attention to insecticides as they cancause resistance in aphids . That is, aphids become resistant to insecticides and no longer cause any effect. Therefore, it is necessary to alternate and combine the different active substances of these products to avoid the appearance of resistance.

Natural enemies of aphids

The biological control of aphids is based on using other insects to help us kill them . We must be careful because the use of insecticides can also kill these beneficial insects for the garden. Therefore, it is better to try to carry out those cultural practices that favor this natural regulation than to apply insecticides. The most effective insects to fight aphids are:

  • Predators: They are those insects that feed directly on aphids. The most common are ladybugs , lacewings , hoverflies , spiders or carabids .
  • Parasitoids : They are small wasps that lay their eggs inside the aphid where their larvae develop and in this way the aphid will die. It could really be a horror scene in a movie theater for aphids…! If you are good observers and want to know if you have this type of wasp in your garden, you simply have to look for mummified aphids . That is, aphids that do not move and have a small hole where the wasp has come out after feeding on the inside of the aphid. I leave you a photo below.

Home remedies to control aphids

As for homemade and ecological methods to kill aphids, there are a lot. Below we list the most used:

  • Infusion of garlic or onion . In both cases the garlic (5 cloves for 30 minutes) or the onion (1 onion for 5 minutes) are boiled per liter of water. It is allowed to cool, strain and spray on the plants.
  • Surely you have heard of the soapy solution to kill aphids. It is indeed one of the easiest and most effective methods used in the garden. We simply have to dilute a tablespoon of neutral soap in a liter of water and spray.
  • We can also apply neem, horsetail or tansy oil .

In this way we can kill the aphid in a natural, effective and homemade way, reducing the use of chemical products in our orchards and gardens. You can find more natural remedies for aphids in the post about organic insecticides for garden pests .

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