Spider mites are slow moving spiders which grow up to 1mm long, they have 8 legs and are typically red and can change colour in the different seasons to green or a yellowy-brown and are barely visible with the naked eye. Also known as the two spot spider mite, they are found underneath your leaves and feed off the sap within the leaf. In the right conditions one female can lay up to 20 clear eggs a day and once hatched they can start reproducing within five days and can live up to 4 weeks. They thrive in hot, dry, warm conditions.
Underneath the leaves you will see a thin web made by the spiders. Where the mites suck the sap out of the leaves, this will leave a white/cream scorching and discolouration on the top sides of the leaves resulting to a reduction of photosynthesis, which may lead to them falling off and in severe cases the plant may die.
If you think you have them but are unable to see the little critters, place a white piece of paper underneath the leaves of your plant. Shake the leaves over the paper and with a magnifying glass you will be able to see them slowly moving around. Place your infected plant in a shady, moist, damp area, remove all dead or dying infested leaves and discard within a plastic bag. Get a hose with good water pressure, aim the water at the affected areas under the leaves and this will dislodge them off. (Careful not to have the water pressure to high as this may rip the leaves) This may need to be repeated as necessary. If it’s a relatively small plant in a pot, you could tip the whole thing upside down and dip the foliage in a bucket of water, this will drown the mites. Regularly check any nearby plants to make sure the mites don’t move onto them, you could even try putting them in isolation if it’s possible. Another way is to use an insecticidal soap sprayed directly onto the spider mites, once the soap starts to dry the spiders will stick together and become a statue, they then die of starvation. Sounds horrible I know but it’s better than using pesticides. This will need to be repeated until they have all been hit. Before spraying your plants with soap, always test a small area first before main application, as certain soaps can damage young shoots. There are also a number of predatory bios available to buy on the internet which is also a great way to keep them under control as they reproduce twice as fast as the spider mites, but they can be expensive.
Remember not to spray soap or water on your plants at the hottest part of the day, this will scorch the leaves, always try and water in the morning.