Aphids, mealybugs and scale on carnivorous plants

Telling the three pests apart

All three are sap-sucking insects, and all three can show up on carnivorous plants despite their diet. The NC State Extension plant profiles list aphids, mealybugs and scale among the pests to watch for on Sarracenia and Nepenthes ^{[4, 5]}, and Kirstenbosch notes that aphids, mealybugs and thrips deform the new growth of sundews ^[6].

All three can leave sticky honeydew, which grows black sooty mold, and ants feeding on that honeydew are a clue ^{[7, 8, 3]}. The ICPS also reports whiteflies on some carnivorous plants and asks growers to check with a hand lens ^[9].

Normal versus a problem

A few insects on a carnivorous plant are expected, since many are prey. A small number of sap feeders may be tolerable too: UC IPM notes that established plants generally outgrow aphid damage and that healthy plants tolerate low mealybug numbers ^{[7, 8]}. The ICPS makes the same point about Sarracenia, with a warning: mealybugs may not seriously hurt a healthy plant, but they can finish off one that is already doing poorly ^[2]. Act when you see colonies, distorted new growth, honeydew, or a plant that is already stressed. The troubleshooter helps separate pests from growing problems.

Aphids

How to check. Look at new leaves and flower stalks. Aphids feed on soft new growth ^[7], and in New South Wales botanists found many flower stalks of naturalized Cape sundews infested with them ^[10]. The ICPS checklist says aphids love Venus flytraps and cause deformed leaves ^[1]. Watch for lacewing eggs too: lacewings eat aphids, so the ICPS reads their eggs as a sign that an aphid infestation is close by ^[9].

What to do. Remove aphids by hand or prune out infested parts ^{[6, 7]}. UC IPM suggests knocking them off sturdy plants with a strong stream of water and keeping ants away, because ants protect aphids from their natural enemies. Outdoors, lady beetles, lacewings and syrphid fly larvae all feed on aphids ^[7]; the ICPS shows a syrphid fly, whose larvae eat aphids, feeding on nectar at a Sarracenia pitcher ^[11].

About sprays. UC IPM recommends insecticidal soaps and oils for aphids on ordinary garden plants but notes that some plants are sensitive to them ^[7]. For sundews, the Kirstenbosch notes say never to use a soap-based insecticide ^[6]. Systemic insecticides reach aphids hidden in curled leaves but are more toxic to beneficial insects, and UC IPM reports that since January 2025 they have been available in California only to licensed pest control professionals ^[7].

Mealybugs

How to check. The ICPS lists Sarracenia, Nepenthes and epiphytic Utricularia as the usual hosts. Mealybugs hide where leaves attach to the crown or stem and can also live on the roots. They are usually noticed late: by the time white fluff appears away from the crown, the colony has outgrown its hiding places ^[2]. In Sarracenia, the thatch of old brown leaves at the base is an ideal breeding ground ^[12]. Females of most species lay 100 to 200 or more eggs in cottony sacs ^[8].

What to do.

1. Trim or pull off all brown leaves, and clear litter and weeds from the pot, so the insects have fewer places to hide ^[2].
2. Keep ants away from the plants, because ants tend mealybugs in exchange for honeydew ^[2].
3. Swab the plants weekly with cotton swabs dipped in 70% rubbing alcohol with a few drops of dish detergent added; the mixture dissolves the wax that protects the insects. The ICPS calls this much safer than spraying ^[2]. UC IPM gives similar advice for houseplants, with a reminder to test a small part of the plant first and watch for leaf burn ^[8].
4. Keep checking and repeat. The ICPS notes that insecticides do not kill the eggs, which is why treatments have to be repeated ^[2].

About insecticides. The ICPS says there is no spray-and-forget solution. It describes knocking populations down with insecticides at two-week intervals, possibly indefinitely, but warns that some of these products kill aquatic carnivores such as Aldrovanda and Utricularia, kill many tuberous sundews, damage other sundews and butterworts, and can deform Venus flytrap leaves ^[2]. Its butterwort guide repeats that certain pesticides will harm and possibly kill Pinguicula ^[13]. UC IPM adds that the waxy coating and hiding habits of mealybugs make contact insecticides less effective ^[8]. If you do use a product, choose one labeled for your situation, follow the label, and test it on a few plants before treating the rest ^[14]. For a badly infested plant, UC IPM’s advice for houseplants is to remove it ^[8].

Scale insects

How to check. Look for small, immobile bumps on leaves and stems. UC IPM separates two common types: armored scales are small and flat, with covers that usually lift off and no honeydew, while soft scales are larger, rounder, produce honeydew, and have covers that do not lift off. Heavy infestations can yellow, distort or kill leaves ^[3].

What to do. None of the carnivorous plant sources reviewed here gives a scale treatment. UC IPM’s general advice is that insecticides are unnecessary unless the damage is intolerable, that ants tending scales should be controlled, and that natural enemies should be protected; for smaller plants it suggests a thorough horticultural oil spray timed for when crawlers are active ^[3]. Given the warnings about sprays on carnivorous plants, test any product on a single plant first ^{[14, 2]}.

Keeping pests out

• Quarantine new plants, including nursery plants, and check the leaf bases again a few weeks later, since eggs take time to hatch ^[2].
• Clean old brown leaves out of Sarracenia clumps when you divide or repot ^[12].
• Keep ants off plants and benches ^{[2, 7]}.
• Inspect new growth and flower stalks regularly, and treat early ^[1].

Fungus gnats around the pot are a separate problem, covered in fungus gnats. For the plants most often affected, see the Venus flytrap, Sarracenia and Nepenthes pages.