Understanding and Controlling Red Mites: A Comprehensive Guide
Red mites are tiny arthropods classified as Arachnida and members of the Tetranychidae family, along with hundreds of different species. They are distributed worldwide and are a persistent concern for growers in warm, arid, and dry weather regions.
Red mites’ presence in fields could go unnoticed until infestation reaches a critical point were damage to plants is visible.
Red mites life-cycle
The life cycle of red spider mites involves several stages of development, including eggs, larvae, nymphs, and adults.
When weather conditions are right, the female red mites lay eggs on the undersides of leaves or the stems of the host plant. The eggs hatch into larvae, which then develop into nymphs. The nymphs molt several times as they grow, eventually becoming adult mites.
The entire life cycle of a red spider mite can be completed in as little as 5 to 10 days, depending on the temperature and humidity conditions. This means that red spider mites can produce several generations per year, with the exact number of generations varying depending on the specific species and the local climate.
How do they spread?
One way that red spider mites can migrate is by the wind. They are small and lightweight and can be easily carried by the wind from one plant to another. This can be especially problematic in greenhouses or other enclosed growing spaces, where the mites can migrate between plants more easily.
Another way that red spider mites can migrate is by hitching a ride on humans or animals. For example, the mites may be carried along if an infested plant is moved from one location to another. Similarly, if an animal brushes against an infested plant and then moves to another plant, the mites may be transferred in this way.
Finally, red spider mites can also migrate by crawling from one plant to another. This is more likely to occur when plants are near one another and can be particularly problematic in gardens or greenhouses where many different types of plants are grown nearby.
How to spot them?
Red mites are tiny and difficult to see without magnification. To spot red spider mites, it is helpful to use a magnifying glass or hand lens with at least 10x magnification.
To look for red spider mites, you should focus on the undersides of leaves, as this is where they tend to hide. You should also check the stems and the base of the plant, as well as any flowers or fruit that may be present. Red spider mites may also be found on other parts of the plant, so it is important to examine the entire plant thoroughly.
When looking for red spider mites, you should be on the lookout for small, reddish-brown insects that are about the size of a grain of salt. You may also see fine webbing on the leaves, indicating that red mites are present. If you are having trouble spotting the mites, you can try gently shaking the leaves or tapping the plant gently to encourage the mites to move.
Shaking the plant above a white sheet of paper can effectively spot red mites, as the mites will fall onto the paper and be easier to see against the white background. Hold a white paper beneath the plant and gently shake the leaves and stems. This will cause any red spider mites present to fall onto the paper.
It is also helpful to check for other signs of an infestation, such as yellow or discolored leaves, leaf drops, or stunted plant growth. These may be indicators of a red spider mite infestation, even if the mites themselves are not immediately visible.
Why is it challenging to control red mites?
First, they reproduce quickly and can build up large populations in a short amount of time. This makes it difficult to control them with chemical pesticides, as they may quickly build up resistance to the pesticides being used.
Second, red spider mites are small and difficult to see, making it hard to identify infestations until they are well established. They also tend to hide in the undersides of leaves, making it difficult to spot them and apply pesticides directly to them.
Finally, red spider mites can be easily spread from plant to plant, either by wind or by humans and animals moving infested plants or soil. This means that even if you can control an infestation on one plant, the mites may quickly spread to other plants in the area.
In the following, we will concentrate on the important aspect of biological control. To read more on conventional methods, refer to our treatment page.
Phytoseiulus persimilis is a predatory mite that feeds on plant-damaging mites, such as spider mites. It is often used as a biological control agent to control spider mite infestations in agricultural settings, including in the cultivation of bananas.
Phytoseiulus persimilis is native to South America but has been introduced to other regions to control spider mites. It is a small, reddish-orange mite with a translucent body. It feeds on all stages of spider mites, including eggs, larvae, and adults.
In addition to feeding on spider mites, Phytoseiulus persimilis also feeds on pollen and nectar from flowers. It is active at temperatures above 15°C (59°F) and has a relatively short life cycle, with a generation time of about 10-14 days.
Phytoseiulus persimilis is considered to be effective at controlling spider mite infestations, but it is not a silver bullet solution. It is important to monitor the population of predatory mites and spider mites to ensure they can keep the red spider mites population in check. In addition, Phytoseiulus persimilis may not be effective in controlling certain species of spider mites, so it is important to identify the specific type of spider mite causing the problem to determine the most appropriate control measures.
There are several ways to apply Phytoseiulus persimilis in gardens and fields to control spider mite infestations:
- Purchase and release: Predatory mites can be purchased from biological control suppliers and released directly onto plants infested with spider mites. It is important to follow the supplier's recommendations for the appropriate number of mites to release per square meter of infested plants.
- Inoculative release: In this method, a small number of predatory mites are released onto the plants at regular intervals over an extended period. This helps to establish a population of predatory mites that can maintain control of the spider mites.
- Augmentative release: This method involves releasing a larger number of predatory mites onto the plants simultaneously to quickly reduce the red mites population. This is typically used for severe infestations or when a quick reduction in the spider mite population is needed.
It is important to monitor the population of predatory mites and spider mites after releasing Phytoseiulus persimilis to ensure that the predatory mites effectively control the spider mites. In some cases, it may be necessary to release additional predatory mites if the spider mite population increases again.
It is also important to consider the environmental conditions when applying Phytoseiulus persimilis. The mites are more effective at controlling spider mites at higher temperatures and when the relative humidity is below 70%. In addition, it is important to avoid applying pesticides that are harmful to predatory mites, as this can reduce their effectiveness at controlling spider mites.
Red spider mites are small, reddish-brown insects that can infest a wide variety of plants. They reproduce quickly and can build up large populations in a short amount of time, making them challenging to control. Red spider mites are difficult to see and tend to hide on the undersides of leaves, making them hard to spot and treat. They can also be easily spread from plant to plant by wind or humans and animals moving infested plants or soil. To effectively control red spider mites, it is important to use a combination of methods, including physical removal, natural predators, and chemical controls, and to be diligent in monitoring for and quick to treat any new infestations.