Mealybug

[Gee.S]

I have been wrestling with mealies for quite some time now, and IMHO, they are just the worst. Systemics are not especially effective because plants do not generally absorb and spread these noxious chemicals evenly throughout, and mealies can move to areas where the sap they are sucking tastes less bitter (and is thus less toxic).

A larger issue is the delayed hatching thing. When conditions are less than ideal a certain percentage of mealy eggs may delay hatching for many months. That is why plants which have been treated and apparently cleansed often suffer re-infestation as much as a year later.

All one can do is inspect plants on a regular basis and treat with one toxic chemical or another as soon as discolored spots appears in upper leaves. But in the end, this is control and not elimination. I suspect the only avenue toward elimination may be disposal of infested plants.

So, I still have a mealie issue. I doubt they will ever be eliminated so long as I continue to cultivate agaves. I also grow lots of non-agaves, but have never seen mealies bother any of them. One thing I've come to understand is that agaves are definitely not all the same to this living pestilence. The appearance is that some agave species seem well able to fend mealies off, while others succumb to infestation in the worst possible way. Agave sisalana for example, seems utterly defenseless. Once mealies have established a presence on sisalana, it is good as dead. There is no saving it. And mealies always attack sisalana toward the base, rather than the core, so they are not easily noticed while the plants start subtly sliding downhill. A. macroacantha is another species especially at risk, though its small size lends itself toward successful chemical intervention.

Bottom line is, if mealies are about, don't waste your efforts trying to grow agaves they seem to prefer. Even if you're able to contain the issue, mealies almost always come back, and reinfested plants may serve as contaminant sources for their neighbors.

[meridannight]

I have been wrestling with mealies for quite some time now, and IMHO, they are just the worst. Systemics are not especially effective because plants do not generally absorb and spread these noxious chemicals evenly throughout, and mealies can move to areas where the sap they are sucking tastes less bitter (and is thus less toxic).

A larger issue is the delayed hatching thing. When conditions are less than ideal a certain percentage of mealy eggs may delay hatching for many months. That is why plants which have been treated and apparently cleansed often suffer re-infestation as much as a year later.

All one can do is inspect plants on a regular basis and treat with one toxic chemical or another as soon as discolored spots appears in upper leaves. But in the end, this is control and not elimination. I suspect the only avenue toward elimination may be disposal of infested plants.

So, I still have a mealie issue. I doubt they will ever be eliminated so long as I continue to cultivate agaves. I also grow lots of non-agaves, but have never seen mealies bother any of them. One thing I've come to understand is that agaves are definitely not all the same to this living pestilence. The appearance is that some agave species seem well able to fend mealies off, while others succumb to infestation in the worst possible way. Agave sisalana for example, seems utterly defenseless. Once mealies have established a presence on sisalana, it is good as dead. There is no saving it. And mealies always attack sisalana toward the base, rather than the core, so they are not easily noticed while the plants start subtly sliding downhill. A. macroacantha is another species especially at risk, though its small size lends itself toward successful chemical intervention.

Bottom line is, if mealies are about, don't waste your efforts trying to grow agaves they seem to prefer. Even if you're able to contain the issue, mealies almost always come back, and reinfested plants may serve as contaminant sources for their neighbors.

It's curious to me how some growers seem to have such a difficult time with them. I have a few show up here and there -- I get them with succulent plants that originate from Dutch greenhouses. But none of my plants even show damage from mealy bugs much less expire from them. I mostly just squish them manually and that's that. Lately I've started seeing them on my ferns, but again, no visible damage on any plants (I still kill the bugs of course).

It's a whole different story when it comes to thrips. Personally, I haven't met a worse pest. I had them at some point (again, got them with plants of Dutch origin) and those vile things ate everything -- including my Agave and Aloe seedlings! They hatch from eggs on a daily basis once you have surpassed a certain threshold in numbers and they destroy whole large plants even if there isn't such a huge number of them. Seedlings will just stop growing and 1-2 thrips seem to be able to kill the plants easily. I used lambda-cyhalothrin on them, which is a fast-acting contact insecticide, and surprisingly it eliminated them all (I had already become resigned to the fact that I'd never get rid of them).

I have used the same substance on plants that were really badly infested with mealies and it seems to kill them as well. But a few mealies always seem to escape for some reason. Still, I recommend giving it a try. Good thing about it is that lambda-cyhalothrin stays active on plant surfaces for about 10 days (depending on climatic conditions such as sun exposure), so it will usually kill the 'stragglers' and newly hatched bugs after spraying as well. You have to wear personal protective equipment and be mindful of where and when you spray but once you wrap your head around it, it's easy to do. Can't use it too often though, for the insects can develop a resistance for it's a pyrethroid.