Thanks Claire for you help. Nature is amazing, huh. I'm not even sure how these guys eat the leaves, mining or not. Can't see their mouth. ericwi , these photos are taken just recently(like yesterday, the day I posted it here), and yes I live in Malaysia. Strange bugs are everywhere in this planet ,we just have to look closer. Anyway the bugs are feeding on the leave of a small tree. And there are a few ladybirds(4 spots) there but they are not bothered by them too. Isn't ladybird carnivorous? This bug is looking more and more mesmerizing to me.

What fawnridge and wisconsintom said. The part of the plant which is dying is the rosette which flowered. But under the dying leaves, around the trunk, there may be baby plants -- new rosettes -- and if there aren't any currently, there may/will be more soon. You can cut off the bloom stem now, or if you want seeds, you can let the seeds mature and maybe plant some. Do an image search for agave "seed pods" to see what seeds and ripe seed pods look like. HOWEVER, your photos of the stem show new leaves among the dried flowers -- and I believe those will turn into baby plants! (Something similar happens occasionally on daylily flower stems: I have a tiny daylily which started that way and is spending the winter with my houseplants.) Here's a page which talks about this process. Unfortunately it doesn't give information about planting the plantlets or bulbils, but the C&S forum folks can probably help: http://www.azfcf.org/docs/DAC/Bulbils.Blackburn.pdf

this is the heirloom garden forum

LOL! Thanks, Jean001a ... it always happens. I search and search and come up empty. Then, a few minutes after posting this plea for help, i find the darned thing. I've got the affected succulents well-sprayed with neem oil. Then, i'll apply marathon to them, as well as other plants as a preventative measure. Zero tolerance for bugs! :) cheers, shireen