There is one pest you will want to keep at bay if you’re growing succulents- mealybugs. This soft bodied insect is very common and it is pretty much inevitable you will come across them on your succulents at some stage. It is very important that when they do make appearance, they are dealt with immediately.
Sometimes mealybugs can be missed as they burrow themselves in the tightest spots where the leaves meet the stalk. And this is how a full blown infestation can happen very quickly. They keep spreading out of sight until there is too many.
So what do you do? Pesticides may be the first thought, but mealybugs build resistance to pesticides and are well protected by a cottony cocoon. I have tried many pesticides claiming to control mealybugs but so far have not come across one that kills all mealybugs, especially the adults. Some people swear by 70% isopropyl alcohol, but in our experience it is not 100% effective either and can easily burn foliage.
Drowning mealy bugs can be a good idea, though there is a 'but'.
Drowning mealybugs can work, but there is a chance the plant will drown as well. To kill mealybugs by drowning the whole plant will need to be submerged for more than 24 hours.
Bigger the infestation, higher the likelihood some mealybugs will survive the drowning attempt.
We've done an experiment and submerged a plant where a mealybug egg has hatched, for 48 hours (we filmed this and the video is available below).
The result? Some mealybugs have died but some survived even after being under water for two whole days days!
The plant did not look that well either, but it has survived after losing much of its leaves. The plant we chose for the experiment is Echeveria 'Fantastic Fountain. This plant does not like water all that much and has to be kept under cover during heavy and frequent rain, otherwise it develops dark spots.
I can well imagine the more ‘touchy’ plants susceptible to rot such as Echeveria Romeo, Lauii, Cotyledon Tomentosa or other succulents that like to be on the dry side would not survive this experiment.
In conclusion, I would not recommend drowning mealybugs as it is not guaranteed they will all drown.
We have another article that explains mealybugs in greater detail here- it is worth reading the whole thing to understand how mealybugs spread and the best ways to control them.