Spider Mite Behavior and Control

Spider mites gained its notorious reputation among gardeners because of their impressive capability to damage garden plants and trees despite their relatively small size. Spider mites came from the arachnid family called Tetranychidae which is a close relative of the common spiders, ticks and scorpions. Spider mites are quite difficult to see without the aid of a magnifying gadget or tool. Moreover, a closer inspection reveals that these arachnids come in a range of colors -- yellow, green, brown, red or the combination of any of these main colors.

In Colorado, spider mites are considered as a major garden pest. In places as such, spider mites can thrive to reach a very big population that an infested garden plant or tree can die because of severe cell damage caused by spider mite bites. When spider mites attack a specific portion of the plant or tree, light flecks or dots will appear giving that specific portion a speckled appearance. Following this early sign is the rapid discoloration of leaves resulting to premature fall-outs. When this condition persists, the plant or tree is most likely to die.

Two types of spider mites are most dreaded by gardeners. These are:


1. Two-spotted Spider mite

This spider mite specie is scientifically known as the Tetranychus urticae, but let's just call it two-spotted for easy referencing. The two-spotted can feed on many types of vegetables, flowers and fruits so they can make the most damage to any type of garden. They can also feed on common house plants. Although the Two-spotted has a lot of predators, because of its proficiency in producing webbing, they are usually secured in their nesting place. Most predators like lady bugs and beetles cannot penetrate through their webbings. Because of this, the Two-spotted can cause unprecedented damage to the plant it chooses to infest.

2. Spruce Spider mite

This spider mite is also known as Oligonychus ununguis. The Spruce is popular among gardeners too because of their unexplained liking for any plant that's green. Their topmost favorites are the Spruce and the Juniper. They can also affect big trees like the giant elm, oak and ash.

Spider mite Behavior

Like all members of the arachnid class, spider mites also develop from eggs. A female spider mite can lay a dozen eggs at a time. She usually lays her eggs near a leaf's vein for added protection. Relative to the size of the female spider mite, the eggs are somewhat oversized. When the eggs hatch, the egg shells remain in the webbing. These remains are quite useful to spider mite exterminators when it comes to identifying the extent of the infestation.

As an adult, each spider mite specie has its own way of protecting itself from the changing climate. For example, two-spotted and honey-locust adults hide under bark cracks and other covered portions of the plant or tree during winter in order to keep themselves warm and well-protected. The common adaptation characteristic of all spider mites is camouflaging. They can change their body colors in order to suit the climate that they are currently experiencing. According to some researches, their colors can greatly affect their internal body temperature making them more adaptable to the changing climate. For example, as winter approaches, spider mites start to change colors from brown, yellow or green to red or orange. That's how they got their nickname "red spiders".

Since spider mites hide during winter, most of their activities happen during warmer months. Spider mite population rises alongside temperature rise. They also develop very rapidly in a warm climate. In fact, it only takes one week for a newly hatched spider mite to become full-grown and lay eggs of its own. In general, a female spider mite can lay a dozen eggs each day for weeks. This characteristic is the main reason why spider mites have become so troublesome to gardeners since it is also during this season that most plants thrive best.

During the hottest months, spider mites also reach their biggest number. During this time, many of their predators cannot stand the lower humidity of the surrounding thus giving the spider mites more opportunity to roam around and feed on plants. Moreover, it is also during this season that many plants start to dry-out, a condition that benefits spider mites the most because it makes the sap of the plant more nutritious to them.

Spider mite Control

Gardeners are still lucky because so many insects and bugs feed on spider mites. These insects are also naturally occurring in areas where spider mites are. Examples of these are the big-eyed bug, thrips, lady beetles and minute pirate bugs. In fact, some pest control products manufacturers have utilized natural predators for biological spider mite control. These commercial insectaries culture these predatory mites and send them to their clients through mail order. So in terms of natural control, Mother Nature has already done a good job.

However, because predatory mites have an increased level of need for humidity, their effectiveness in controlling spider mites is also limited during dry seasons, the very time when the population of spider mites is at its peak. Insecticide manufacturers are also reluctant to release chemical spider mite control products because these products can also kill the natural predators of spider mites, something which can actually worsen the problem.

A few pesticides that target spider mites only have been developed, but these pesticides are very expensive. It would be counter-productive for the gardener to spend so much on pesticides alone and have a total yield that is almost just equivalent to what is spent. Thus, the best method currently applied by gardeners is the use of predatory mites coupled with the right water management system. The water system is designed to keep the humidity in the garden at a reasonable level for the predatory mites to thrive. To do this, forceful water jets are periodically fired to plants and trees. The process in itself can also kill spider mites on the spot, including their eggs.