Perhaps you'll find answers here: https://extension.msstate.edu/sites/default/files/publications/publications/p2938.pdf

Ah, well several of the Crape Myrtles on a previous property were severely infested with these several years ago. And they, in turn, attracted a colony of Acrobat ants, that harvested all their "honeydew." This double-whammy effectively stopped the growth of these specimens, and many of their branches became blackened, dry, dead, and brittle...

But then finally (about a year after I noticed the severity of the situation) on one of these shrubs, all those scales just naturally attracted a large colony of ladybugs...that started feeding on them.

So, what was the final result? Well, I'm not exactly sure, as I left before long... But, those shrubs are still there today, and from what I vaguely recall, looked healthier. Although I haven't really bothered inspecting them up close again to specifically check on their scale infestation level?*

* Reason being, Crape Myrtles are overused, non-native landscape shrubs, IMO. Now, they ARE pretty, not invasive, and relatively benign...but I'm also not going to shed any tears for them, lol... So, I didn't really care how they were doing anymore, lol.

I'm not familiar with invertebrates in your part of the world but I'm pretty sure the second picture doesn't show ladybugs.

^^ Oh, you'd be surprised at what different ladybugs look like in other parts of their life cycle! Most ladybug larvae and their molted skins do actually look like spiky shells.

And some ladybug larvae can even look like mealybugs - so it's really important to learn to recognize all phases of beneficial insects so that you don't accidentally kill the wrong ones!

BTW, I also did actually see a huge amount of mature ladybugs on that tree too, so I am pretty sure that the casings I posted were their molted larval skins...

As I said, I'm not familiar with invertebrates in your part of the world. But I would recognise any of the stages shown in your illustrations as being ladybugs. They are just like the ones in my region. So, no, I would not 'be surprised'. The creatures in your photo just didn't look like any of the ladybug instars I know.

blakrab, the scale picture you've shown is not the crape myrtle bark scale. And the images you say are predaceous ladybug larvae.....aren't. They might be the larvae of other beetles.....where did you find the pictures? I saw them on other websites, but not properly identified.

The plot thickens. I thought the second picture was from blackrab's own garden. That was the implication.

OP, I had it on three of mine, a while back. I tried the soil drench, with no success ... and I’m not saying they don’t work, it just didn’t in my situation for whatever reasons. I bought a spray at my local nursery, and that did work. I’m sorry I can’t remember the brand, but I do remember using it in April of that year, and waiting around two weeks to spray again. I’d ask for a good product at your local nursery. I know Texas A&M has been working hard at finding the best treatments, so there may be even better products since I treated mine.

Excellent information in the link Jean first referred to :-) I would base and time any treatments based on the info contained in that publication.