Known as Tetranychidae in the scientific world, and simply Spider Mites to cannabis and hemp farmers, these common crop destroying pests seem to come with the job description. There are many subspecies of spider mites, and our focus today is on the Two-Spotted Spider Mite. Some of the unique species of spider mite are much more easily identified than others; however, it is generally unwise to try, as their control measures, damage and biology are all the same.
Identification & Life Cycle
Spider mite populations WILL proliferate under the right conditions. Unfortunately, these conditions exist in many indoor grows - basically, warm with very little wind. Infestation damage can be identified by the telltale sign of the webbing they produce on your cannabis/hemp fan leaves. Inspecting for spider mites has become a daily chore for many grower teams. What your team needs to understand is that by the time you see webbing, it may be too late to control the population.
The four life stages of Spider Mites:
The species females lay between 50-100 eggs throughout their lives with unfertilized eggs hatching as males and fertilized eggs hatching as females. Spider Mites often begin to hatch their eggs within 72 hours.
The length of a spider mite's life cycle depends specifically on their environmental conditions, with the ideal temperature being the major contributing factor. An entire spider mite generation can be completed in under a week if all conditions are favorable for rapid growth.
How Spider Mites Damage Your Plants
Spider Mites damage plant leaf matter by ingesting juices from the fan leaves. Additional signs of spider mite damage are curled up and "burned" leaf edges, as well as leaves that have taken on a silky leather-ish texture. The silky webbing is predominant when mite populations have boomed within your grow.
Clean your cultivation environment, focusing on all of the little cracks and crevices indoor farmers sometimes miss. We start with washing all surfaces of the cultivation area and inspect ALL plants for spider mite presence, webbing, or damage before planting.
You can also minimize mite damage and reproduction rates by reducing water and nutrient stress as much as possible. If you are growing outdoors, hyper-focus on your cultivation area and help your plants through hot spells, which will help control spider mite populations.
The Best Method: Organic Biological Controls
This is ideal for spider mite control during your cannabis/hemp flowering cycle. Learn to introduce beneficial mites as a proactive measure after knocking down larger spider mite populations for continued monitoring and successful eradication.
Predatory Mites are an effective organic biological control for use against the two-spotted spider mite. These natural enemies do not injure plants, feed on other insects, or bite human beings. Once released, these predatory mites will immediately begin searching for water and a food source on the underside of your cannabis/hemp leaves. Your biological control measures of a small to medium infestation should occur naturally within three to four weeks.
As a farmer dealing with massive outbreaks in a commercial facility, a second release is usually required to stay aggressive with organic eradication methods. On severely infected plants, silk webbing and feeding marks will be visible. You must reduce the pest infestation before releasing your predatory mites. Consider spraying with organic insecticidal soap, BUT ONLY if your cannabis or hemp plants are still in the vegetative growth stage.
Here’s a rough guide for how many predatory mites you will need to control a given infestation:
• 1-2 per Infected Fan Leaf
• 20-30 per Medium-Sized Plant
• 2,000 per 700+ Square Feet
Well Known Spider Mite Predators (Effective for Cannabis & Hemp Issues):
Well Known Spider Mite Destroyers (MOST Effective for Cannabis & Hemp Issues):
When the right proactive steps are taken, controlling and eliminating spider mites using biological methods is not difficult. It just takes some careful observation and attention to your plants, and knowing the right predatory mites to use. In this way, you can avoid using any toxic chemicals and/ or ruining the flavor of your crop.
About the Author
Daniel Enking is the founder of Everflux Technologies. He is a life-long environmentalist and practical dreamer who is obsessed with resource efficiency and imaged an "everything recycling machine" at age 10.