Red Spider Mites

Red spider mites (RSM), scientifically known as Tetranychus urticae, are small arachnids belonging to the Tetranychidae family. RSM are typically small, ranging from 0.4 to 0.5 millimetres in size. They are usually reddish-brown in colour, but this can vary depending on their diet and environmental conditions. The two dark spots on either side of their bodies are distinctive markings that aid in their identification.

Life Cycle

RSM undergo an incomplete metamorphosis, meaning they develop from egg to nymph to adult without a pupae stage. They can complete their lifecycle in as little as 5-20 days, depending on temperature and humidity levels. These mites reproduce rapidly, with females laying dozens of eggs over their lifespan, which can be as short as a few weeks. Eggs, commonly situated beneath leaves, start off transparent but later become opaque. Larvae emerge as straw-coloured with three pairs of legs, shifting colour after feeding and becoming inactive before progressing to larger protonymphs with four pairs of legs. Protonymphs display varying shades of green and follow a feeding-resting pattern akin to larvae before maturing into deutonymphs. Males elongate while females grow rounder and larger at this stage. Following another feeding-resting phase, they moult into adult mites. 

Damage

RSM are commonly found in warm and dry environments, infesting a wide range of plants including ornamentals, fruits, vegetables, and various crops. These mites are plant pests, feeding primarily on the sap of plants. Typically found on the underside of leaves, they pierce cells to extract contents, leading to yellowing and cell death. Damage manifests as yellow spots on leaf surfaces, progressing to entire leaf yellowing and chlorophyll loss, wilting and potentially resulting in plant death. 

Control

Phytoseiulus Bottle
Phytoseiulus Bottle

Control of red spider mites often involves integrated pest management (IPM) strategies such as the introduction of predators such as Phytoseiulus persimilis or cultural practices like pruning infested plant parts when there’s dire infestation. 

Understanding the behaviour and lifecycle of red spider mites is crucial for effective management and prevention of damage to crops and plants. Regular monitoring and early intervention are key to minimizing their impact on agriculture and horticulture. 

 

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