COMMON PESTS AND DISEASES - Cultivating Carnivorous Plants (2015)

Cultivating Carnivorous Plants (2015)


Unfortunately, every carnivorous plant grower will, at some point, encounter a plant pest or disease.

These are unavoidable, unless the impossible is achieved and every plant is started from seed in a sterile

environment and kept in a similar environment for the duration of its life. Most pests will, unfortunately, be

brought into a collection through trades or purchases of unknowingly infected plants. As with all gardening,

some growers and nurseries are better about watching for and treating pests than others. Still, some exposure

to pests is inevitable.

The best possible way to combat pests spreading to a collection is to isolate newly acquired plants for 1-

2 months. This isolation period will allow plants - which may have arrived looking healthy - to exhibit signs

of any pests or diseases they may be carrying. While such quarantining may seem burdensome, it is much

easier to place a potted plant in a plastic bag for a month than to treat an entire highland Nepenthes collection

for a Thrips infection in the dead of winter.

The second best way to combat pests and diseases is to give plants their proper light, temperature,

humidity, and water requirements. A healthy plant is less likely to get infected, and better able to survive

treatment. Ensuring that Sarracenia are getting full sun, that highland Nepenthes are getting cool nights, and that

Heliamphora is placed in a high humidity environment can prevent those plants from encountering many

dangerous pests and diseases.


Aphids, also known as plant lice, are tiny, sap-sucking insects that usually attack

Dionaea, Drosera, and Sarracenia plants. Numbering some 4,400 species, it would be

impossible to give a detailed account of how to get rid of aphids. Generally, non-

soap, non-aerosol-based insecticides work well and do not do too much damage to

the plants.

Aphids can come in

Natural pest control remedies, such as Lady Bugs, are often recommended to

many colors, but

new growers. In my experience, Lady Bugs are prone to becoming trapped by Drosera

green and orange are

leaves and Sarracenia pitchers, so I would not recommend attempting to use Lady

the most common.

Bugs with those two genera.

Exyra Moths

Exyra moths are a Sarracenia-specific pest. These nasty moths lay eggs in Sarracenia pitchers. The eggs hatch



and the larvae eats the pitcher. Signs of infection are typically obvious before the larvae reaches the rhizome.

Any infected pitchers should be cut from the plant and burned or sealed in a plastic bag before being thrown

away. Leaving infected pitchers on the ground or composting them risks future generations of Exyra moths

being born, or larvae surviving to infect other plants.

Fungus: Dampening Off & Others

Fungus can take a serious toll on

seedlings, dormant plants, and, rarely,

growing plants. Often, fungus will appear

on the surface of the soil and appears to

spread towards seedlings. The first line of

defense should be scraping off the surface

of the soil and allowing it to dry out more.

Additionally, consider removing dead

vegetative matter and exposing the soil

surface to brighter light, particularly


A good second line of defense is to

add a small portion of hydrogen peroxide

(H2O2) to water and spray that mixture on

the fungus. A 3% hydrogen peroxide

solution - the strength commonly found in

drug stores - diluted with one-to-four parts

water will kill the fungus without harming

Botrytis cinerea fungus on a grape.

the plants.

For more serious fungal infections, or before placing plant rhizomes and hibernaculum in the

refrigerator for dormancy, consider treating these with a non-copper-based fungicide. Note, however, that

these will often cause deformations in plant growth, and great care should be taken to avoid contact with

these chemicals as they often have harsh, negative effects upon humans.

Japanese Beatles, Caterpillars, and Other Chompers

The greatest threats for outdoor collections are

large, chomping insects. These will often be able to do

significant damage to a collection before pesticides take

effect and often have a large territory, preventing

effective treatment with pesticides. Encouraging the

development of a diverse garden ecosystem should result

in predators eating many of the large, chomping insects

doing damage to an outdoor collection.

While it may be tempting to feed some of these

chompers to the very plants that they have been eating,

avoid doing so. Often, they will be able to eat their way

out of otherwise deadly traps. In doing so, they will

Japanese Beatles

further injure the collection.




Mealybugs are related to scale,

but, instead of small, hard shells,

mealybugs have soft bodies and

often appear to look like little bits

of white cotton. Treatment is the

same as with scale - insecticides





mealybugs. Small scale infections

can be treated with cotton balls or

cotton swabs dipped in rubbing





treatment is necessary.

Do not attempt to use ants as

a natural treatment as many species

of ants will actually protect

mealybugs and encourage their

growth and development. This is

because mealybugs secrete a liquid


that ants harvest for food.


One of the most common pests for growers to

encounter is scale. There are around 8,000 species of

this pervasive pest, and it is one of the few that can

appear on plants a month-or-two after initial

infection without other signs. Scale - like Thrips - is

one of the primary reasons plants should be isolated

for a month or two after being added to a collection.

Some places, such as Hawai’i, have endemic species,

such as Pinnaspis strachani, which have a thirty day

lifecycle, meaning signs of infection may not be seen

until up to a month after plants leave that


Small infections can be treated with cotton-

balls or cotton-swabs dipped in rubbing alcohol, but

this treatment will only kill the adults. Harsh

pesticides, such as Orthene, or diverse pesticides,

such as Talstar, are good choices for treatment.

Several treatments will be necessary over the course

of several months for complete eradication. Some

pesticides, such as Orthene, are prone to weakening

plants and can easily kill growth tips on genera such

as Nepenthes. ( Nepenthes hamata, dubia, jamban, and

Scale on a Nepenthes leaf.

their offspring appear to be particularly vulnerable).



Whenever a scale infection is found, the affected plants should be isolated immediately. Scale is

particularly prone to spreading to nearby plants. One infected plant can infect an entire collection within a

week. Therefore, proactive isolation and treatment is necessary. Fortunately, signs of infection are usually

fairly obvious - small, hard bodied “scales” appearing on new growth or near growth points.


Thrips damaged Nepenthes leaves.

Thrips are, next to scale, the most problematic pest that can attack carnivorous plants. Unlike scale,

Thrips are much harder to spot. If plants appear to be suffering and conditions appear fine, it is likely that

they are infected by Thrips.



The best way to determine

whether Thrips are present is to

disturb the plant by blowing on it or

tapping it during warm temperatures.

Within a second or two, the small

(less than 1 mm) insects will be seen

to run or fly off the leaves of the

plant. Given their small size, it is

often best to examine a plant for

Thrips by using a magnifying glass.

Infected leaves can be cut off,

but, often, the infection will have

spread across the entire plant and

throughout the collection by the time

it is noticed. Due to the tiny size of

Thrips and the difficulty in spotting

them, treatment should occur on all

plants within the vicinity of the plants

known to be infected.

Thrips must be treated with a

Thrips-specific insecticide, such as

Avid. General-use insecticides, such

as Orthene, are not nearly as effective

against Thrips, and, often, actually

have no impact. As with general-use



insecticides are often harmful to

humans, so precautions such as

A young Nepenthes leaf heavily damaged by Thrips.

rubber gloves, protective eyewear,

and masks are necessary.

Sarracenia Root-Borer

Sarracenia Root-Borer is an awful, grub-like pest. Thankfully, it only infects Sarracenia and is not a

common pest. A common sign of infection is a small hole atop a Sarracenia rhizome with wood-pulp colored

powder around the outside of the hole. Over time, the infected plant will wilt as the borer infects the plant


Infected plants should be destroyed immediately. The chance of the root-borer surviving and destroying

other plants is too great to allow infected plants to stay within a collection. Infect plants should be dug up,

along with some of the surrounding soil, and sealed in a plastic bag prior to disposal at a landfill.