Thrips

You may notice some flying bugs around your plants, see very tiny speck like translucent, yellow, brown, or black insects crawling on your columns with oblong bodies, mainly near tips in crevices between ribs. In advanced infestations you may see a tan colored uneven scarring, scabbing, corking, often starting at new growth and spreading downward. The cacti will later grow new green flesh up through this scab. Unlike fungal spots (which are often sunken, black/soft, or clearly circular), the damage looks superficial, textured like fine sandpaper, and is concentrated heavily at the crown of the plant. These are indicators you are dealing with the pests known as thrips - Thysanoptera. A great diagnostic tool is to place some yellow paper sticky traps near the columns. After you catch a few flying insects, inspect them closely compared to photos of adult flying stage thrips to confirm.

Understanding the thrip life cycle is critical for effective treatment.

• ** Egg:** 2-6 days. This insects eggs are laid directly into plant skin tissue, completely protecting them from insecticides and physical removal.
• ** Larvae/Nymphs:** 4-8 days. The very tiny young insects feed by sucking the plants juice on sections of new growth and hide in between ribs.
• ** Pre Pupae & Pupae:** 2-4 days. They stop eating, and drop down in or near the soil.
• ** Adult:** 2-4 weeks. Flying stage. Adults breed and females lay 50-300 additional eggs.

Warmer temperatures speed up the lifecycle timeline, cooler temperatures slow it down.

Thrips can be introduced into collections and gardens several ways.

• ** New Additions:** Introducing a new plant to the garden is the number one cause of sudden indoor or greenhouse outbreaks. Because females lay their eggs inside the plant tissue and pupae live in the soil, a newly acquired cactus or companion plant can look 100% clean under a magnifying glass but explode with larvae a week later.
• ** Infected Substrate:** If you use unsterilized outdoor soil, compost, or bulk organic materials in your potting mix, dormant pupae can be introduced right into the root zone of your pots.
• ** Outdoors:** Outside, thrips can come from nearby plants, weeds, soil, or even on the wind.

• ** Weather:** Thrips are most active in warm weather with low humidity. Higher humidity leads to fungal pathogens that naturally kill thrips.
• ** Nutrition:** Excessive nitrogen, insufficient calcium or silicon in ratio will lead to thin, easily penetrated skin that thrips will thrive on.
• ** Stagnant air:** Lack of airflow creates conditions for thrips to spread and thrive.
• ** Insecticides:** If collections are sprayed indiscriminately with broad spectrum insecticides, natural predators will be eliminated and thrips will rebound from their eggs and pupae in no time.

• ** Spinosad:** If available in your area, Spinosad concentrates that do not contain soaps or oils is a top choice of treatment options. Tested and confirmed highly effective when used properly. Spinosad is food crop safe. Read and follow the label. Plants should be sprayed at dusk or lights out to prevent burns. Spinosad will affect insects that actively feed on your plants, so it will not kill eggs or pupae. Repeat applications 4-5 times, 4-5 days apart each to completely eradicate infestations. Spinosad works against most sucker class pests.
• ** Flying Skull Nuke Em:** This is an alternate product that is applied the same way as Spinosad, also food crop safe, but uses a different active ingredient - citric acid. Tested and confirmed also highly effective. This product works by essentially melting the insects on contact while the spray is wet. It theoretically works on all life stages, but eggs are often protected by being deep inside plant tissue, and pupae commonly in the soil, so repeat applications are still required.
• ** Natural Predators:** Releasing some beneficial natural predators into your grow space can be an effective method of control. Lacewings, Cucumeris mites (Neoseiulus cucumeris),Hypoaspis miles (Stratiolaelaps scimitus), and Nematodes are common choices that are highly effective.
• ** Beauveria bassiana:** This is the active ingredient in a range of products that act as a fungal attack on arthropods. Fungal spores will infect and kill the insects that touch the wet spray. Highly effective against all insects that touch the wet spray. Food crop safe. Requires 4-5 repeat applications 4-5 days apart. This product is NOT a top choice because it is a broad spectrum insecticide and will kill beneficials and pollinators, but it may be a good choice for indoor grows if top choice options are not available.
• ** Diatomaceous Earth (DE) & wettable sulphur:** DE an be mixed heavily into the soil or mixed 50/50 with sulphur to dust the plants. This is NOT a top choice because it is non-selective and will harm beneficial insects and pollinators. Additionally, growers must wear a mask when handling to avoid inhaling the dust, which is hazardous to the lungs. Dusting will damage farina and permanently alter plant skin appearance.
• ** Oils and soaps:** NOT RECOMENDED - Neem oil, horticultural oil, soaps, and products containing these are often recommended as treatments to various pests. Not only are they not as effective as the top choice treatments listed here, but also oils will block stomata pores, preventing plant transpiration and causing moisture blisters.