Common insects

Spider Mite

Spider mites are not true insects and are closely related to spiders and other arachnids. They can be found indoor or outdoor and cover plants with visible webbing and lay round translucent eggs. Spider mites are tiny (< 1 mm) and damage plants by sucking on leaves. Spider mites overwinter on the underside of leaves and other protected places, then the populations begins to grow dramatically in late spring or summer as they move to the upper side of leaves, fruits, and vegetables. In milder climates, spider mites may continue to feed and reproduce year round. Spider mites are prolific reproducers and can complete a life cycle in one week if the conditions are right.


Leaf stippling and yellow or brown spots may be a sign of light spider mite infestations. Heavy infestations may result in bunches of dried leaves, leaf loss, and abundant webbing. Severe damage can kill plants and affect crop yield.


Spider mites are a common pest which should be monitored year-round and treated with selective miticides. Spider mites can also be controlled by many natural enemies including predatory mites and other insects.

Pyrethrins are botanical extracts derived from chrysanthemum flowers and are commonly used as miticides for spider mite control. Pyrethrin sprays also can affect flavor quality less than synthetic chemical based products. HydroWorxx Mite and Insect Killer contains organic pyrethrins plus canola oil. The pyrethrins kill the adult mites and the canola oil smothers the eggs, providing multi-life stage control. HydroWorxx Mite and Insect Killer is OMRI listed for use in organic gardening, and can be sprayed up to the day of harvest.


Aphids are small, soft-bodied insects that cause damage by sucking on plant parts. Aphids are common on many plants and aren’t usually harmful to plants in lower quantities. Heavier infestations can cause aesthetic damage to plants, slow plant growth, transmit plant diseases, and decrease crop yields. Natural predators often feed on aphids, eliminating the need for pesticides. When pesticides are necessary, use less-toxic products such as insecticidal soaps and oils that are less likely to affect the beneficial insects.

To prevent aphids:

  • Avoid over-fertilizing by using organic or slow-release products.
  • Closely monitor plants that aphids typically build up on, such as cannabis and vegetables. Treat as necessary to prevent population explosions.
  • Keep ants off plants to help natural enemies control aphids. Some ant species have a mutualistic relationship with aphids, where they protect aphids from their natural enemies as they feed on the honeydew that the aphids release.

To reduce aphids:

  • Remove infected leaves and stems.
  • Shake the plant or spray it with a strong stream of water to physically remove aphids.
  • Protect seedlings with covers or mulches.
  • Wait for weather changes, such as late freezes or hot weather, when aphid populations may naturally decrease.
  • Protect beneficial insects by avoiding the use of broad spectrum insecticides that can be toxic to them.

If aphids are still a problem after using the above physical measures, or for a faster solution, insecticides might be your best bet:

  • Choose less toxic products such as insecticidal oils and soaps that selectively target soft-bodied insects. When properly used, these materials solve most insect problems. HydroWorxx Insecticidal Soap is proven to be very effective on aphids. Not only does it kill the insect on contact, but it also can be used up to the day of harvest and is OMRI listed for organic gardening.
  • Insecticidal soaps work by disrupting the phospholipid cell membranes, causing the cells to “leak”. Apply these products thoroughly to all parts of the plant where aphids may be hiding.


Adult whiteflies are tiny, plant-sucking white insects, sometimes with dark markings on their wings. Interestingly, most of the plant damage is caused by nymphs - oval, wingless insects that use piercing mouthparts to suck plant juices from leaves, and produce honeydew. Prevent whitefly problems by pruning infested leaves, physically removing whiteflies from leaves with water, using reflective mulches, choosing less susceptible plants, and eliminating pesticides that kill whitefly’s natural enemies. Beneficial insects can also be encouraged by avoiding dusty conditions and by controlling ants, which may form a mutualistic relationship with whiteflies. Ants feed on the honeydew produced by whiteflies and in exchange protect the whiteflies from natural predators.


  • Install a reflective mulch in your vegetable garden to protect young plants.
  • Use hand removal and sticky traps to reduce whiteflies.
  • Avoid hot, dusty growing conditions that favor whitefly development.
  • Use pest sprays. If you decide to treat, choose products that are least harmful to natural enemies—such as insecticidal soaps — and combine their use with the other practices listed above. HydroWorxx Insecticidal Soap, for instance, is OMRI listed and has demonstrated high efficacy against whiteflies. Good spray coverage, including the underside of leaves, is essential as the product must directly contact the pests to be effective. Repeat applications might be required.

Fungus Gnats

Fungus gnats are small dark flies about 1/16 to 1/8-inch long, with light gray wings, slender legs, and long antennae. Fungus gnats infest sources of organic matter, like soil or other container media, in greenhouses, nurseries, and houseplants. Their larvae mostly feed on organic materials in soil such as fungi, and severe infestations can damage plant roots. Fungus gnats can develop quickly, with a new generation produced in 17 days in certain conditions.


Fungus gnat larvae can cause significant harm to roots and stop plant growth, especially in seedlings and young plants. Large populations usually appear in moist, organically-rich soil. Overwatering plants can exacerbate fungus gnat damage, as larvae feed on rotting roots and fungi in saturated soil. Adult fungus gnats, however, don’t damage plants and are considered a nuisance pest.


Sticky traps may be used to monitor fungus gnat pest pressure. The most effective control methods target the immature, damaging life stages in the soil rather than attempting to control the adult gnats. Preventative methods, such as reducing needless moisture, will minimize fungus gnat issues. Biological control agents, such as predatory hunter flies, can also control this pest. You may use pyrethrin-based sprays such as HydroWorxx Mite and Insect Killer for immediate knock down.


Thrips are tiny insects, less than 1⁄20 inch long, that damage plants with piercing, sucking mouthparts to feed on the contents of plant cells. They can be difficult to detect until damage occurs because thrips often feed while hidden in buds or shoot tips; therefore they are often a difficult pest to control. Thrips can cause aesthetic damage to ornamental plants, decrease marketability and yield of commercial crops, and spread plant diseases. Fight thrips with good cultural care, pest exclusion, planting of thrips-resistant species, and by protecting natural enemies by using least-toxic insecticides.

Signs of thrip infestation:

  • Speckled spots on leaves, flowers, or fruit.
  • Distorted or dead leaves and other plant parts.


  • Avoid using pesticides that are toxic to natural predators.
  • Don’t apply excess water or nitrogen fertilizer.
  • Remove damaged plant parts.
  • Protect small plants with mesh covers or cages.
  • Cover soil with reflective mulch, to repel flying thrips.


Canola oil and pyrethrins can provide control of thrips. HydroWorxx Mite and Insect Killer, which contains botanical pyrethrins derived from chrysanthemum flowers, is a good alternative to synthetic pyrethroids. HydroWorxx Mite and Insect Killer kills thrips on contact and is listed for use in organic gardening.


Scales are small insects that are parasitic on some plants. They appear as circular or oval-shaped raised areas on bark, leaves, or fruit. Scales cause damage by sucking plant juices, which can cause yellowing or leaf loss. Many scales also excrete honeydew which can promote the growth of black sooty mold.


  • If there are naturally occurring predator insects, avoid the use of systemic insecticides. HydroWorxx Mite and Insect Killer is a contact insecticide that contains pyrethrins and canola oil and is effective against advanced infestations of scale. It is for organic gardening and can be used up to the day of harvest.
  • Some types of scale form symbiotic relationships with ants, whereby the ants move the scale insects to favorable positions and protect them from predators in exchange for honeydew. In these situations, controlling ants will help control scale insects.
  • Remove and replace heavily infested plants.