Unfortunately from time to time Nepenthes
fall prey to pests that can injure, mutilate, disfigure, and even destroy
the plant. Luckily, with careful observation, most fatal pest problems
can be eliminated before your plant goes permanently south! Since I grow
all my highlanders outdoors without using a greenhouse, they are vulnerable
to more pests than Nepenthes grown in isolated environments. This is by
no means a comprehensive list of every pest that attacks Nepenthes. I imagine
a person growing Nepenthes in the Eastern part of the United States will
encounter some different pests that I haven't encountered here in California.
However, I can provide some "red flags" or observations from my experiences
that may help other growers respond to their Nepenthes' needs when they
Scale: This insect is my biggest problem.
You can see them as little brown, cyst-like circles on the stem and leafblade
of the plant. They are usually hard and crusty. Often, they like to attack
the stem of the Nepenthes below the surface of the moss so they are hard
to detect right away. I know right away when I have a scale infestation
because of the ants! Scale produces honeydew as a waste product that ants
love. Ants also can spread scale too. If there appears to be leaf deformation
and wilting, this is another indicator that scale could be present. A healthy
Nepenthes generally doesn't produce twisted, deformed leaves. I usually
scrape the scale off with a long toothpick or "BBQ" wooden Kabob spear.
If the infestation is more serious, then I scrape off the scale and spray
the entire plant with a pesticide.
Mealy Bugs: Mealy bugs are white
ovate shaped guys that love to get into small crevices of the plants to
do their damage. They are easy to see because of their white, almost furry
appearance. If you see white tufts under the leaves, those are eggsacks
laid by the parents. I haven't had too many problems with these guys. Mealy
bugs tend to be more of a problem with my Sarracenias than my Nepenthes.
Ants are another "red flag" that Mealy bug may be present. Mealy bug produces
honeydew like scale does that ants love. Ants move Mealy bugs to other
plants as well. Mealy bugs can get below the soil level so if you see them
dig down around the stem of the Nepenthes to check out how bad the infestation
might be. Mealy bugs suck out the plant's juices so look for wilted, deformed
leaves and stems. If you have a bad infestation then uproot the plant,
spray off the entire plant with water, (optional; spray with an insecticide
as well), and repot in fresh potting media.
Aphids: Aphids have not been a big problem
for me. Aphids like new growth so they will attack the growing tendril
usually. Older, waxy leaves seem to be impervious to aphid attack. Since
aphids are usually on the growing tips of Nepenthes, you can simply spray
them off with water or use a sundew carnivorous plant to pick them off
as well! I've done this with Drosera capensis. They love aphids! I rarely
use an insecticide with aphids because they haven't been an issue.
Slugs and Snails: I haven't had much
a problem with snails because my Nepenthes are either in hanging baskets,
or on tables that the snails can't reach. I have had small slugs get into
the moss and do some damage. You can tell when a slug has got after a Nepenthes
because there are "chew" marks on the leaves and tendrils. Also, they will
lay their clear, gelatinous eggs in the moss that pose a potential threat
as well. I've never used a pestcide on Nepenthes for slugs. With careful
inspection, I can usually pick them out of the moss before major damage
is done. My biggest concern is putting a small size 2 plant, like N. villosa,
outdoors and then in the evening a slug trucks through and demolishes it.
That hasn't happened yet but is always a concern.
Whitefly: My Nepenthes have not fallen
prey to these pets. They're relatively easy to spot. They look like small
white things fluttering around the plants. Especially when the leaves are
disturbed. Whiteflies lay their eggs on the underside of the leaves in
circular ringlet patterns. To date, I haven't had any problems with whitefly.
Some Sarracenias have had a minor outbreak. I usually use an insecticidal
spray on the underside of the leaf to treat the plant instead of spraying
the whole area.
Fungus and Root Rot: This disease is
outside of my experience and expertise. I've seen the results of root rot
though. The plant becomes dessicated and wilted looking. Like it's not
getting enough water. Then the plant dries up and dies. For some reason
the growing tip is the first part to wilt and die followed by a blackening
of the growing stem. Once the plant gets this bad, it's hard to salvage.
This is usually the result from poor air circulation and chronic overwatering.
My outdoor Nepenthes get plenty of air circulation and drainage so this
problem I've never encountered. However, my lowlanders indoors could be
vulnerable. I do tend to keep them on the wet side and air circulation
is diminished. My best advice would be to throw any excess water from catch
saucers and monitor the soil appearance. Soil shouldn't stink too much
and the moss should be green.
Pesticides should be used as a last resort
for treating plants. Obviously because they are chemicals, they could harm
or even kill your Nepenthes. It's hard to go into a nursery and find people
who have good information about pesticides for carnivorous plants. I have
yet to find one label that lists carnivorous plants and how to treat them
for pests. Most of my experience has come from treating orchids with the
same pests as my Nepenthes as for which pesticides to use. I've experimented
with a few different kinds and the one that works the best for me is Ortho
Systemic Insect Killer. Formerly called Isotox. The label states that it
protects the entire plant from chewing and sucking insects. Perfect! I
mix up a gallon at a time as for the directions on the label. I think it's
about 3 tablespoons or 1 1/2 fluid oz. per gallon of water. I then transfer
the mix into a spray bottle and have at the little suckers. I only spray
what part is infested and try to use it sparingly. I've had no leaf burn,
pitcher drop off, or plant death from using this product. It's great on
Nepenthes, Sarracenias, Flytraps and orchids too because it doesn't hurt
the blooms. Once again, WHAT WORKS FOR ME MAY NOT WORK FOR YOU! When in
doubt, call a reputable vendor who you buy your Nepenthes from and ask
them what they recommend as well. I would imagine they have far more knowledge
than I possess for treating diseases with their Nepenthes.