Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

inside leaves. An infestation of caterpillars or leafhoppers will damage foliage and slow growth, eventually defoliating, stunting, and killing a plant.
    Cultural and physical control: Manually remove.
    Biological: Trichogramma wasps, spined soldier bug (Podisus maculiventris Podibug®).
    Sprays: Homemade spray/repellent, hot pepper and garlic. Bt, pyrethrum, and rotenone
Leafhoppers
    Identify: Leafhoppers include many small, 0.125 inch (3 mm) long, wedge-shaped insects that are usually green, white, or yellow. Many species have minute stripes on wings and bodies. Their wings peak like roof rafters when not in use. Leafhoppers suck plant sap for food and exude sticky honeydew as a by-product. Spittlebug and leafhopper larvae wrap themselves in foliage and envelop themselves in a saliva-like liquid, plant sap.
    Damage: Stippling (spotting) similar to that caused by spider mites and thrips on foliage. Leaves and plant lose vigor, and in severe cases death could result.
    Cultural and physical Control: Cleanliness! Black light traps are attractive to potato beetles.
    Biological: The fungus, Metarhizium anisopliae, is commercially available under the trade name Metaquino®.
    Sprays: Pyrethrum, rotenone, sabadilla.
Leaf Miner
    Identify: Adult leaf miner flies lay eggs that hatch into one-eighth-inch (0.25 mm) long (green or black) maggots. You seldom see the maggots before you see the leaf damage they create when they tunnel through leaf tissue. Leaf miners are more common in greenhouses and outdoors than indoors.
    Damage: The tiny maggots burrow between leaf surfaces, leaving a telltale whitish-tunnel outline. The damage usually occurs on or in youngsupple growth. It is seldom fatal, unless left unchecked. Damage causes plant growth to slow, and if left unchecked, flowering is prolonged and buds are small. In rare cases the damage is fatal. Wound damage encourages disease.
    Controls: These pests cause little problem to indoor crops. The most efficient and effective control is to remove and dispose of damaged foliage, which includes the rogue maggot, or to use the cultural and physical control listed below.
    Cultural and physical control: Smash the little maggot trapped within the leaf with your fingers. If the infestation is severe, smash all larvae possible and remove severely infested leaves. Compost or burn infested leaves. Install yellow sticky traps to capture adults.
    Biological: Branchid Wasp (Dacnusa sibirica), chalcid wasp (Diglyphus isaea), parasitic wasp (Opius pallipes).
    Sprays: Repel with neem oil and pyrethrum sprays. Maggots are protected within tunnels, and sprays are often ineffective. Hemp Diseases and Pests suggests to water plants with a 0.5 percent solution of neem. This solution works fast and stays on plants for four weeks after application.
Fungus Gnat
    Identify: Maggots, larvae, grow to 4-5 mm long and have translucent bodies with black heads. Winged adult gnats are gray to black, 2-4 mm long, with long legs. Look for them around the base of plants in soil and soilless gardens. They love the moist, dank environments in rockwool and the environment created in NFT-type hydroponic gardens. Adult females lay about 200 eggs every week to ten days.
    Damage: Infests growing medium and roots near the surface. They eat fine root hairs and scar larger roots, causing plants to lose vigor and foliage to pale. Root wounds invite wilt fungi like Fusarium or Pythium especially if plants are nutrient-stressed and growing in soggy conditions. Maggots prefer to consume dead or decaying, soggy plant material; they also eat green algae growing in soggy conditions. Adults and larvae can get out of control quickly, especially in hydroponic systems with very moist growing mediums. The adult gnats stick to resinous buds like flypaper ! The gnats are very difficult to clean from the buds.

Leaf miner larvae burrow in the leaf. They cause few problems indoors and are most common outdoors in spring and early summer. Kill them by smashing them between your fingers.

Microscopic fungus gnats are difficult to see with the naked eye.

Scale affix themselves to stems and foliage. They are a minor problem indoors and outdoors.

This nematode attacked the stem. Most often nematodes attack roots. Large knots grow where nematodes damage both roots and stems.
    Controls: The easiest way to control these pests is with Vectobac®, Cnatrol®, and Bactimos®, all contain Bacillus thuringiensis var. israelensis (Bti ). This strain of Bt