Red spider (Tetranychus urticae)

The spider mite is a small mite

The spider mite is one of the most common pests that affect plants, both those living outside and inside the home. Although we say "spider" it is actually a mite that multiplies very quickly, so if nothing is done to prevent it it causes many problems for crops.

With all this in mind, I'm going to explain everything you need to know about the red spider: its biological cycle, symptoms and damages, and of course how you can combat it with both ecological and chemical remedies.

Origin and characteristics

The spider mite is a pest that affects many plants

The spider mite is a mite native to Eurasia, but today it is found almost everywhere in the world. Its scientific name is Tetranychus urticae, and It is characterized by measuring about 0,4 - 0,5mm long and having quite long legs. It is red in color when mature and feeds on the cells of the leaves.

Biological cycle

The life cycle of the spider mite it's relatively short: a female lays her eggs on the leaves during the summer and, as soon as they hatch, the larvae emerge, which will begin to feed on the plant cells. Soon after, they turn into proto-nymphs and then deutonymphs. These specimens will be greenish, but as they approach adulthood they will turn a deep red.

As a curiosity, you should know that females that have had offspring survive the winter in a physiological state of latency called diapause.

Symptoms and damage

The spider mite spins cobwebs between the leaves

It is quite easy to detect this pest, since the spider mite spins webs between the leaves. But in addition to this symptom, there are others that should make us suspect:

  • Leaves: yellowish spots appear in the area of ​​the bite and small reddish dots on the underside.
  • Fruits: dark spots appear that give it a dirty appearance.
  • Others: general weakening, growth arrest, flower abortion.

Control and elimination

Chemical remedies

There are many plants that can be affected by the spider mite, such as fruit trees and the vast majority of ornamentals. If we have one with a major pest, that is, it has spiders all over the leaves and you can see that it is having a bad time, then the best we can do to help it is to treat it with chemical remedies.

Now, you have to know that these products are toxic to humans and other animals, so it is very important to wear rubber gloves -like the ones used to wash the dishes- every time we go to use them.

Which are? Well any acaricide will do us. Active ingredients that are effective to eradicate it are abamectin, ethoxazole or propargite, among others, but I insist, any anti-mite product will rid our plants of these annoying parasites.

So that problems do not arise, in addition to putting on gloves, we must read and follow the instructions specified on the product's packaging, and use it only if:

  • it's not windy
  • no short-term rain forecast
  • the diseased plant is separated from the healthy ones

Thus, we will achieve our goal.

Home remedies

Diatomaceous earth, a very effective home remedy against pests

Diatomaceous earth

Home remedies are the most recommended, especially when the plague has not yet spread much. These products and practices are not harmful to animal health or the environment. They are as follows:


  • Diatomaceous earthThey are microscopic fossilized algae composed of silica, which is what glass is made of. It is like a very light white powder that does not leave any residue whatsoever, but when it comes into contact with the parasite (be it red spider, cochineal ... even with fleas it works lo) what it does is break what would be the shell - forgive me microfauna connoisseurs to use that word - which protects it. Thus, it dies dehydrated after 1-2 days. The dose is 35g for each liter of water. You can buy it for example here! as well as in stores of those that sell everything (I think for animals, fruits, etc.).
  • Natural predators: they are mites and some bedbugs that feed on specimens of red spiders. They can be found in specialized stores.
    • Neoseiulus californicus
    • Phytoseiulus persimilis
    • Conwentzia psociformis
    • Stethorus punctillum
    • Feltiella acarisuga
    • Nesidiocoris tenuis
  • Cultural practices: they are a set of preventive measures that it is advisable to do to prevent the plague from appearing.
    • Spray outdoor plants with lime-free water during the summer. Of course, always at sunset or first thing in the morning. Keeping this routine will keep the plants quite protected, as this pest does not like humid environments.
    • Water and fertilize the plants whenever necessary: ​​if they are properly hydrated and fed, it will be difficult for them to end up being victims of pests. For this reason, it is very important to water whenever necessary (more frequent in summer than the rest of the year), and to pay them from spring to late summer / early autumn with specific fertilizers or, better, with ecological.

We hope that with these tips you can keep the spider mite away from your crops. 🙂

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