Keeping Clivia Clean: Snails, Slugs, and the Pests That Matter
Daniel Pretorius · 5 min read · 24 August 2026
Clivia are tough, long-lived plants, but a healthy collection is a watched collection. Most trouble comes from a short list of familiar culprits, and almost all of it is easier to prevent than to cure. What follows is a practical, seasonal guide to keeping Clivia clean: the snails and slugs that every grower learns to hate, the sap-suckers like mealybug, the amaryllis borer that can hollow out a plant from the inside, and the rot that follows a pot left too wet. The guidance draws on the Clivia Society standards and on long-established growing practice.
Snails and slugs, the classic enemy
Snails and slugs are the pest most Clivia growers meet first. They are soft-bodied and legless (a snail carries a coiled shell, a slug does not), they leave a tell-tale shiny slime trail, and per the Clivia Society standards they are active only in damp conditions. They feed at night on the softest tissue: the tender new leaves in the centre of the fan and, worst of all, the emerging flower scape. A single night's grazing on a rising bud can spoil a whole season's flower.
The first line of defence is not a bait at all, it is hygiene. Snails and slugs need damp and darkness by day, so remove their hiding places: clear dead leaves and debris from around the crown, lift pots off the ground where you can, keep the area under the benches tidy, and avoid watering late in the day so the surface is dry by nightfall. Hand-collecting after dark with a torch, especially after rain, thins their numbers quickly.
For active control, two organic methods are worth knowing. Beer traps (a shallow container of beer sunk to soil level) draw slugs and snails in overnight and drown them; they need topping up and emptying every few days. Iron-phosphate (ferric phosphate) baits are the pick of the pellet options: the slugs eat them, stop feeding, and die, and the active ingredient breaks down into iron and phosphate in the soil. They are far safer around pets, children, and wildlife than the older metaldehyde baits, which remain effective but are genuinely toxic and best avoided in a garden used by animals. Scatter thinly, per the label, and refresh after heavy rain.
Mealybug and other sap-suckers
Mealybug is the next most common complaint. Per the Clivia Society standards they are small (about 3 mm), oval, light-pink, slow-moving insects covered in white waxy threads, with two longer threads at the tail. They shelter in the tender growth and, typically, deep in the leaf sheaths at the base of the plant, where they disfigure the emerging leaves. They are made worse by overcrowding, poor airflow, and heat, they excrete a sticky honeydew that grows black sooty mould, and they can carry viruses. Ants often farm and move them, so a trail of ants at the base of a plant is worth a closer look.
Spacing and airflow come first: give plants room, and thin an overcrowded clump. For a light infestation, a cotton bud or a firm jet of water dislodges the colonies. Where more is needed, mineral oil or neem oil are the lower-toxicity options, worked into the leaf bases where the insects hide, and repeated about a week later to catch the next generation. Because they burrow into the sheaths, thorough coverage matters more than a strong dose.
The amaryllis borer
The amaryllis borer, also called the lily borer, is the pest that does the most damage. Per the Clivia Society standards its scientific name is Brithys crini, and it feeds on Clivia, Crinum, and Hippeastrum. Grey-white moths fly at dusk and lay eggs on the undersides of the leaves. The caterpillar that hatches is black with yellow bands, and it does the harm: it tunnels down inside the leaf toward the centre of the plant, and if it reaches the growing point it can kill the plant outright. The tell-tale sign is a pale, sub-surface tunnel visible between the upper and lower leaf surfaces.
Timing is everything. The borer is most active in the warm months, roughly October to April, so inspect several times a week through spring and summer. The single most effective habit is to turn the leaves over and rub off the eggs before they hatch, and to squash any caterpillar found while it is still inside a leaf. For a bad season, Bacillus thuringiensis (the strain sold for caterpillars, Bt kurstaki) is a low-toxicity biological spray that the caterpillars eat and die from, and it spares bees and other insects.
Crown and root rot from overwatering
Not every problem is an insect. The most self-inflicted trouble is rot, and it almost always traces back to water. Clivia are semi-epiphytic: their thick roots evolved in leaf litter with air around them, and they rot in a mix that stays wet. Overwatering, a heavy or slow-draining mix, or water sitting in the crown invites both root rot and bacterial soft rot (commonly Erwinia), which turns the centre of the plant into a foul-smelling mush.
Prevention beats treatment. Grow in an open, free-draining medium (composted pine bark is the South African standard), keep the crown at or just above the surface so water does not pool in it, and ease right off watering through the cool winter rest. If rot does appear, act early: lift the plant, cut away every trace of rotten tissue with a clean blade, let the wound callus and dry, treat with a fungicide, and repot into fresh, better-draining mix. Sterilise the knife between plants so infection is not carried from one to the next.
An honest word
No collection is ever completely pest-free, and it does not need to be. The aim is not eradication but a routine: right mix and drainage, shade and airflow, sensible watering, a tidy bench, and a regular walk through the plants with the leaves turned over, most closely from spring through autumn when both borer and snails are busy. Caught early, almost every problem here is a small one. Reach for the least-toxic control that works, follow the label, and keep the strong chemicals as a genuine last resort.