Rooibos Has Three Real Insect Pests, and Almost Nothing Registered to Spray on Them

An Agricultural Research Council survey of cultivated rooibos in the mid-1990s turned up 110 insect species living on the bush. Of those, 40 were feeding on it directly, and only 21 behaved like pests at all. In the decades since, growers and entomologists have narrowed their real attention down further still, to three: a leafhopper, a looper caterpillar, and a moth whose larva bores straight into the root.

That is a different file from the one on rooibos's fungal die-back, the branch-killing infection that shares the plant's own scientific name (the fungus with rooibos's own name). This one you can actually see: hopping, looping, or on the wing.

What the leafhopper does to a leaf

The leafhopper is Molopopterus theae, described by the entomologist Theron in 1978 and, by most working accounts, the most persistent of the three. It does not chew a leaf the way a caterpillar does. It pierces the tissue and draws sap out of it, and a field with a real infestation shows the damage as chlorosis first, the leaf losing its green in patches, then in heavy populations a scorched look across whole plants. Growth slows. In extreme cases the plant dies, and the damage is worse in a dry summer: a plant already short of water has less capacity to withstand the added stress of an insect feeding on it.

Molopopterus theae is not left to its own devices in the field. A strepsipteran, a small parasitic insect called Halictophagus calcaratus, lays its own larvae inside the leafhopper's body, a form of biological pressure that exists in the field whether or not a grower ever sprays. It is not, by itself, a control program. But it is one reason the leafhopper's numbers are not the whole story: rooibos's insect problem already has a working, if partial, insect solution living inside it.

A caterpillar that measures as it moves

The looper is Isturgia exerraria, a geometrid, and it earns its English family name from how it moves. Lacking a full set of legs down its body, it draws its back end up to meet its front, arches into a loop, then reaches forward again, an inching, measuring stride. Afrikaans-speaking growers in the Cederberg call it by the same logic in a different language: a landmeterwurm, a land-measurer worm. English got there through Greek (geo, earth, plus metron, measure); Afrikaans got there through its own two working words. Neither language borrowed the image from the other. Both looked at the same caterpillar and reached for the same metaphor.

The looper is also the hardest of the three to catch early. Its eggs are pale green and sit directly on the leaf they will hatch on, effectively invisible against the foliage. Once it has fed and is ready to pupate, it drops into the soil beneath the plant that fed it, an orange-brown pupa roughly 10 millimetres long (a bit under half an inch), sitting some 15 to 20 millimetres down (about half to three-quarters of an inch), directly under the host. As of Hatting's 2017 review, entomologists were still trialling insecticides against it in search of one worth formally registering for rooibos. No product had cleared that bar yet.

The moth whose larva bores into the root

The clearwing moth is the most physically dramatic of the three and the hardest to see coming. Felderiola candescens (long known in the rooibos literature under an older name, Monopetalotaxis candescens) is a member of the Sesiidae, a family of moths that mimic wasps convincingly enough to be mistaken for them at a glance, in part because of the clear, unscaled panels in their wings that give the family its common name.

Adult moths fly in November and December, the hot, dry start of the Cederberg summer, and lay eggs at the base of young plants. What happens next is the part that makes this pest genuinely difficult: a newly hatched larva bores into the taproot within hours, and from that point on it is feeding inside the plant, invisible and effectively unreachable. Hatting, Brand and Thiebaut's 2013 field trials recorded losses climbing with plantation age (a rough 4 percent in year-one fields, rising to 24, then 27, then 36 percent by the fourth year) as more root systems accumulated more borers over time.

The same trial found a real answer, for this one pest at least: a prophylactic drench of the insecticide esfenvalerate, 10 millilitres (about two teaspoons) of a 0.4 percent solution delivered straight to the stem base of each plant in early to mid-November, gave 97 percent control or better when timed to land before the larvae had a chance to bore in. A parallel attempt at biological control, introducing the fungus Nomuraea rileyi to infect the moth naturally, did not work. For this particular pest, the narrow chemical window is, so far, the only window that has actually closed.

Why so few sprays carry rooibos on the label

None of this reads like an industry well supplied with pest control, and it is not, for a structural reason that has nothing to do with the insects themselves. Registering a pesticide in South Africa for use on a named crop is an expense an agrochemical company weighs against the size of the market buying it. Rooibos is a single-region crop grown on a comparatively small total acreage next to citrus, grapes, or grain, so a product's maker rarely has a commercial reason to seek rooibos-specific registration, even when the chemistry would plainly work on rooibos's pests.

The result is a grower's toolkit borrowed rather than built. A 2025 Farmer's Weekly account of production practice on a Cederberg farm named Mospila, an acetamiprid-based insecticide, as effective against the clearwing moth, though the same account notes it is being phased out over its effects on bees. Delegate, whose active ingredient is spinetoram, gives broad control of the looper, but carries a two-month withholding period before harvest, a real constraint on a crop picked on its own seasonal schedule. Between the two named products and the field's actual list of 21 pestiferous species sits a wide, mostly unaddressed gap.

The three things growers do instead of spraying

Faced with that gap, Cederberg growers lean on practices that do not require a registered chemical at all, and none of the three is new.

The first is scouting: walking the rows regularly enough to catch chlorosis, a scorched patch, or a wilting young plant before the population behind it has grown large. The second is a strip of land deliberately left alone. Farms across the region ring their rooibos plantations with untouched natural veld rather than plant to the fence line, not out of neglect but because that unplowed ground is exactly the kind of habitat that keeps a pest's natural enemies (parasitic wasps and strepsipterans like Halictophagus calcaratus among them) living nearby, rather than displaced to wherever a monoculture has not reached.

The third is the planting cycle itself. A rooibos field is productive for roughly four to five years before the bushes are pulled and the ground is rested under other crops (the full planting-to-retirement calendar lives here); growers do not simply replant rooibos straight back into the same soil. One well-documented case makes the rotation concrete: Willie Nel's Ysterfontein operation, about 4,050 hectares (about 10,000 acres) in total with roughly 1,400 hectares (about 3,450 acres) under rooibos, runs an eight-year cycle by design. A field is planted in year one, harvested through years two to five, then ploughed and left bare for a year to bring couch-grass under control, then sown to lupins, then to oats, both grazed off by sheep and cattle rather than cut, before rooibos goes back in. The lupins and oats do double duty even before they reach the animals, standing as a windbreak for the next planting's seedlings, too young yet to take an open Cederberg gust on their own. The years out of rooibos do more than rest the soil. They interrupt a pest's life cycle along with its host, so a leafhopper or looper population built up over a field's productive years has nowhere to carry over into the next planting.

None of it adds up to a solved problem. The looper still has no registered spray of its own, the clearwing moth's one proven chemical answer still only covers a narrow window early in a young plant's life, and the leafhopper's biggest checks remain a summer drought's own severity and a parasite growers cannot direct. What rooibos has instead of a pesticide aisle is a rotation, a strip of veld left alone, and a person walking the rows.