Red spiders, mites that wreak havoc

The red spider, tetranychus urticae by its scientific name, is a parasite that attacks trees, shrubs, vegetables, flowers and green plants. It feeds on plant sap.

Red spiders are mites. Adults measure less than a millimeter and are virtually invisible to the naked eye. Contrary to popular belief, they are not always red. They can be orange, yellow or even green. Their color varies according to the variety on which they set their sights.

Contributing factors

A hot, dry climate favors the multiplication of red spiders. The use of nitrogen fertilizer or humus-poor soil are also factors that contribute to the appearance of spider mites.

How it works

Red spiders use their stinging stylet to feed. They feed on the cytoplasm present in the external cells of plants. Once bitten by the mite, plant tissues become dull and dry.

These parasites are highly mobile. In just a few days, they can infest an entire garden. And as they cling to your tools and clothes, they spread indoors too.

Red spiders multiply rapidly. They lay eggs in winter and summer. Females mature after just ten days and lay their eggs in turn. Incubation lasts between 4 and 22 days. Larvae become adults in less than three weeks. An adult lives from 10 to 30 days. During the warm season, more than five generations can follow one another!

Symptoms

Stung by a red spider, the plant dries up and dies. To find out if your collection has been invaded, take a close look at the leaves. The bites leave yellow dots that later turn silvery.

You may also notice spider webs between the leaves. These are very fine and difficult to see. The easiest way to remove them is to place your pot on a white cloth and shake it. The parasites will fall onto the cloth, making them easier to spot.

Treatment

Red spider infestation is easily prevented and treated.

Preventive measures

Maintaining a humid atmosphere keeps mites at bay. To do this, mist your houseplants or clean their foliage with a wet sponge. Auxiliary pollinating insects such as ladybugs help combat red spider mites.

In addition, fertilizers containing potash and nitrogen encourage their development. They make crops sweeter. Insecticides are also counterproductive. In fact, red spiders are becoming increasingly resistant to contact with chemicals.

Curative measures

To combat the ravages of this invisible enemy, spray your outdoor flowers with nettle or horsetail manure.

If, despite these preventive measures, you are attacked by red spiders, don't worry: they're easy to get rid of.

A simple spray with a hose is enough to kill them. To be effective, take the time to water the leaves, branches and trunk thoroughly.

If indoor plants are affected, give them a shower. Basin the foliage for a few minutes with lukewarm water. Repeat several times a week to eradicate the colony completely.