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Aphids, Caterpillars, Gnats, Spider Mites, Thrips, Whiteflies, and other pests, oh my!

Insects and mites can really put a damper on your grow. Learn how to defeat each of these and what you can do to prevent them.

Aphids, Caterpillars, Gnats, Spider Mites, Thrips, Whiteflies, and other pests, oh my!

Insects and mites can really put a damper on your grow. Learn how to defeat each of these pests and what you can do to prevent them.

Jump to: Aphids | Caterpillars | Gnats | Spider Mites | Thrips | Whiteflies | Slugs & Snails

It's always a good idea to make sure if you are spraying to turn your grow lights off until spray has had a chance to dry. Droplets on leaves act like a magnifying glass to focus light and will burn your leaves and plants. This also helps to prevent residue build up on lights and bulbs as heat from bulbs will cook residue onto them. In larger grow areas, sprayers and foggers are excellent at dispersing product.


NOTE: Always observe manufacturers warnings and safety precautions in handling and applying products. This includes flushing plants and allowing sufficient time between application and harvest.




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What to look for: Also known as “plant lice” these guys are tiny. You can spot them, but to verify them you need a magnifying glass. They come in a barrage of colors, but can typically be found in a grey to black shade.

Why they’re bad: They suck sap from your plants causing them to turn yellow. They can also attract ants with the honeydew they release.

How to get rid of them: Apply a spray multiple times a day for at least a week up to 10 days.





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What to look for: Chewed leaves or holes in leaves, caterpillars enjoy softer tissues and tend to go for smaller branches on the lower parts of buds. Small black fecal remains can also be a signal that caterpillars have been present, look for this near the buds of the plant. Butterflies tend to lay their eggs at the top part of the plant so look at this area in an outdoor grow to see oval or circular eggs that are often white or yellowish in color.

Why they’re bad: Not only do they damage buds and harm the plant. They also leave behind a fungus called botrytis that rots buds from the inside.

How to get rid of them: Apply Safer Brand Caterpillar Killer to remove caterpillars.





What to look for: Tiny black flies hanging around sweet things like nutrients and grow media.

Why they’re bad: They eat your plant roots and grow media.

How to get rid of them: Sticky fly paper will attract and capture them. It’s a good idea to make sure your grow media isn’t overly damp. Nematodes are a predatory insect that will eat gnats but they can also cause root damage. The best solution is to use a gnat specific spray to get rid of them such as:




You can find a full line of gnat specific sprays at hydrobuilder.com.


Spider Mites


What to look for: Tiny yellow specks on your leaves. Bad infestations will have spider webs around buds and stems.

Why they’re bad: They suck the sap from your plants and one female can lay 100s of eggs in a few weeks.

How to get rid of them: Observe proper grow room sterilization protocols. Quarantine new plants introduced to your grow, and thoroughly clean any objects or plants that enter your grow area. Wipe your feet and make sure your clothes are free from contamination before entering your grow area. Use a spray specifically targeted to spider mites. Even after you see no evidence of mites use a different type of spider mite spray one more time in order to prevent a reinfection. Spider mites can become resistant to a particular type of spray over time so it’s important to vary your tactics each time in order to kill them all, even after you don’t see any evidence of mites.

AzaMax is a great choice to remove spider mites. Another would be Mighty Bomb which is 100% organic.





What to look for: Silver or bronze colored scars on leaves. They like eating developing flowers and are seen in greenhouses more than outdoor grows. While they do have wings they rely more on wind to transport themselves from site to site.

Why they’re bad: They deprive leaves of chlorophyll and cause them to turn brown and crumbly. They are also known to transport plant viruses.

How to get rid of them: Use a spray specially designed to get rid of thrips. We recommend AzaMax and Mighty Bomb.







whitefly Weisse-Fliege

What to look for: Tiny white moth-like creatures flying around your plants and on the underside of leaves.

Why they’re bad: Whiteflies cause diminished chlorophyll creation and spread disease.

How to get rid of them: Use sticky fly paper to remove adults in the air, remove leaves that are more than 50% damaged, spray with insect repellant. One of the best methods to prevent whiteflies is to plant zinnias along with your plants and observe proper grow area quarantine procedures. Never bring in new plants without first inspecting them for infestation and always inspect and clean tools and clothes to remove contaminants.

Whitefly insecticide is available at Hydrobuilder.com


Slugs & Snails


What to look for: Slime trails and slimy creatures, usually between ¼” to 3” in length. They are a variety of colors including white, brown, yellow and can be spotted or striped.

Why they’re bad: They create holes in leaves and, if left unchecked, will eat plants down to the roots.

How to get rid of them: Keep the areas around plants as dry as possible. Bleach sand and salt make an effective deterrent. Broad spectrum pest control gives the best results.





It's been said that an ounce of prevention is worth a pound of cure and in dealing with pests, this is true. Follow these tips for keeping pests away:

  • Always maintain clean grow areas
  • Auarantine new plants to your grow until you are sure that they are free from pests and disease
  • Clean grow areas thoroughly between growing cycles to remove any dead or decaying plant matter
  • Sterilize hand tools and instruments especially if they move from one grow area to another to prevent cross contamination
  • Do not allow pets or animals to enter grow areas, especially if they are indoor/outdoor
  • Always check clothing for pests and contamination before and after leaving grow areas
  • Companion planting can help to deter pests naturally
  • If an infected plant is found it should be removed and quarantined immediately to prevent spread
  • Certain grow media can deter pests such as those that contain diatomaceous earth
  • Neem oil is a preventative natural deterrent.


Questions? Call our experts at 888-815-9763 or email [email protected].