Is this mealy bug ?

[splosh]

strange white waxy droplets occurring on torch cactus and other Trichosurus. I can see no obvious signs of insects, even if I use a magnifier. Tried Neem oil. No luck. Are these mealybugs?

[Steve Johnson]

strange white waxy droplets occurring on torch cactus and other Trichosurus. I can see no obvious signs of insects, even if I use a magnifier. Tried Neem oil. No luck. Are these mealybugs?

Yes, those are spine mealies. See this:

http://www.cactiguide.com/forum/viewtop ... 24&t=42129

Very detailed, and if you go all the way through, you'll see how you can effectively deal a knock-out blow to those nasty little things. By the way, I posted an update recently, so this may be helpful:

http://www.cactiguide.com/forum/viewtop ... 75#p387702

The downside to an Imidacloprid soil soak is that it should not be done for cacti being grown in the ground.

[greenknight]

Steve posted before I could submit this, but here it is anyway:

Looks like it - mealy bugs on spines are a thing, see: https://www.cactiguide.com/forum/viewtopic.php?t=42129

The actual bug is just a tiny thing in the middle of the blob of waxy secretions, to see it dig into the middle of one with a needle.

The neem oil needs to contact the bugs, and that wax gives them protection from it - mix some soap with the neem to help it penetrate.

[splosh]

Thanks for that Steve. Why do you say Imidacloprid soil soak should not be done on in-ground cacti ?
I'm in Los Angeles, & had a bad infestation of Agave snout weavel last year. Never noticed until 2 of my blue glows just fell over. The little weavels live at the base of the plant and roots, so it's near impossible to notice until it's too late.
I used Bonide Tree Shrub control on "in-ground" agaves, and the remaining plants seem fine. I would like to do the same for my torch cactus, but now I'm going to hold off until I hear back.
As to the more immediate problem of the scale mealy bugs. I have tried isopropl alcohol, mixed 50/50 with water and a touch of dish soap.
You seem to suggest this is not a good idea, and that it's ineffective. This method seems to have considerable traction on other sites ?

I noticed the post about methylated spirits. Problem is, It's banned here in CA. I'm really not sure I can go around picking off all the scale mites by hand with tweezers as you suggest. Would take me weeks.
Then they'll just come back.
There must be some other way ?

On the Tetrasan website, it lists the following pests that are controlled
Spider mites:
Citrus red mite
European red mite
Lewis spider mite
Pacific spider mite
Southern red mite
Spruce spider mite
Two spotted spider mite

Not scale mealy bugs though ? Yet you say this stuff works ?
Same goes for Avid. No mention of scale insects on label.


I really appreciate all your advice, but I now feel a bit stuck, and the only real solution is to pick the critters off by hand ?
Many Thanks

[Steve Johnson]

Why do you say Imidacloprid soil soak should not be done on in-ground cacti ?

Neonicotinoids like Imidacloprid scramble the mealies' tiny brains, which kills them, and their eggs won't hatch. That's as it should be. Unfortunately, it also scrambles the brains of bees, and neonicotinoids can do serious harm to bee populations. I grow all of my cacti in pots, so whenever I do soil soaks, I capture the runoff and dispose of the Imidacloprid-laced water at my local home hazardous waste center. Proper containment and disposal is impossible if you're doing soil soaks in the ground, and I simply cannot recommend it for environmental reasons.

On the Tetrasan website, it lists the following pests that are controlled
Spider mites:
Citrus red mite
European red mite
Lewis spider mite
Pacific spider mite
Southern red mite
Spruce spider mite
Two spotted spider mite

Not scale mealy bugs though ? Yet you say this stuff works ?
Same goes for Avid. No mention of scale insects on label.

Miticides work on pest mites, insecticides (like Imidacloprid) work on pest insects. Avid and Tetrasan are miticides that are effective against red spider mites and flat mites, not scale insects. That's why I made a clear distinction between the two types of pest and how to deal with them in my presentation.

The actual bug is just a tiny thing in the middle of the blob of waxy secretions, to see it dig into the middle of one with a needle.

The neem oil needs to contact the bugs, and that wax gives them protection from it - mix some soap with the neem to help it penetrate.

Spence's suggestion may be your only fallback. Spence -- I haven't used neem oil myself, but if mixing it with soap has been effective for you, I'll update my presentation to include this under the list of short-term solutions.

[greenknight]

I haven't actually tried the neem oil with soap, but It's recommended by many sources - I have used soap without neem for root mealy bugs and found it effective, so it ought to work even better with neem added. Worth a try, anyway.

[hegar]

I do use Imidacloprid occasionally (early spring, before cacti flower) as a ground application with irrigation water. I do not believe, that I am doing substantial damage to the environment, including bees; at least I have not noticed a reduction in pollinating insects on my outdoor plants.
I also do not need to worry about the chemical leaching into the groundwater or being carried away with runoff water. We do have the groundwater present at a significant depth and usually receive only around 8 inches of precipitation a year.
I did read and am fully aware of the ill effects that this chemical causes when honeybees forage extensively on Imidacloprid treated flowers.
Therefore I do not even use this insecticide on a yearly basis and apply only some of it to the cacti, if I do notice a bad insect infestation.

As far as mealybugs are concerned I have not seen them in large numbers on my cacti. At one time though, I did have a quite severe infestation of my prickly pear cacti by the cochineal insect, a close relative of the mealybug. Those insects were unsightly, but they did not kill the cacti.
If you were to carefully remove some of the larger fluffy white bodies from your cactus and tease off some of the whitish waxy coating, you should be able to see the insect hiding within. Also, unless you puncture or crush the mealybug, you would also see it move, albeit rather slowly.
To see the insect's oval shape and legs, you will probably need to use a hand lens. I would suggest purchasing one of those with around a 10 times magnification.

Harald

[splosh]

I've tried Neem oil with soap. Had no luck with it.
Steve, I hear you about the bees. My torch cactus flowers were crazy this year, as in the hundreds. Bees were all over them
Anyone tried Bonide systemic insect control? The active ingredient is Acephate.
The other thing I am considering. Australian Lady bugs. Biobee Biocryptolaemus. Their whole diet seems to be mealy bugs. Bit concerned they would get fried in the LA sun. They are not cheap

[Steve Johnson]

From the Greenhouse Management website (https://www.greenhousemag.com/article/g ... anagement/):

"Soil-applied systemics include Kontos, Flagship, Safari, and Marathon/Discus N/G (or generic)."

The only non-neonicotinoid product on the list is Kontos, not harmful to bees, so that's good news. Here's the bad news -- it's expensive:

https://www.ebay.com/sch/i.html?_from=R ... _PrefLoc=1

I can't justify the expense since I have a small apartment collection, but Kontos may be just the ticket for growing cacti in the ground.