Thanks, aurorawa. I destroyed the leaf in a fit immediately after I took a pic (and then changed my clothes, washed my hands lol) so I cannot answer those questions. Derp! I'll investigate further next time.

Let's see if this pic works...

I found another plant with a similar spot (although way more yellowish) so I performed surgery. You can see two small holes where I gently scraped out the spot, left a pock mark, and the debris is on my finger (it's sort of hard, crusty and yellow). I sent a plant to themockturtle and she found similar spots, so um, wonderingifishouldfreakoutornot.

It looks like the leaf got damaged a bit a "bled" sap, which then hardens or callouses over. Doesn't look like a critter to me.

Denise in Omaha

That looks like sap, to me. So, don't freak out! When I was making cuttings of my imperialis, the stumps would drip onto the leaves and plant below, and when it dried, it looked like that. You take cuttings recently, or maybe a vine/stem broke?

Also, regarding the bottom pic, remember different hoyas produce different color saps, ranging from clear, white, green-yellow, yellow, etc. So, the yellow color you scraped off could account for that.

Oh, YAY! Thank you, ladies! I'm pretty rough with my plants, I move them around a lot and pick them up to coo (or shoo) at them, take & break cuttings, so I can see that happening. Phew. I was starting to panic...not so much for myself, but because I've shared so many cuttings & plants with other people, and didn't want to be passing something along. I need to be more gently with my plants!

Now I'm laughing because I just went ham on my plants and brutally inspected every.single.leaf. I suspect I'll be seeing quite a few more incidences of that dried sap...

Lol. I used to fuss over mine, and they kept getting damaged, so now, I only move them when I water, when I take them out for the summer, or in for the winter, and once a month (or two), I inspect all of them for health and to make cuttings. Here is something that may shock you: my pest treatment is really relaxed. I treat with BATS every 4 months, but unless I have a large infestation, or if the rooting cuttings I am selling, get bugs, I don't sweat a scale or two. However, I don't allow mealybugs. Period. They multiply too quickly and do way more damage than the rogue scale does. I have thankfully never had the displeasure of dealing with spider mites.

Here's what I saw: some leaves had semi-translucent spots on the tips. This seems to spread along the margin of the leaves. Some leaves that had more translucent spots/areas also had some irregular shaped yellow waxy spots on the back of the leaves. When I looked at the leaves against the bright light, I could see the translucent areas easily. The affected areas look lighter and the unaffected areas look darker. In fact, I only noticed it when I glanced at the plant by the window and the light was shining through the leaves. I'd imagine it would be very hard to see in thicker leaves.

I don't think it's scale. I'm thinking it may be a leaf damage related to high humidity or some bacterial infection caused by humidity and heat. Has anyone seen anything like this?

That particular plant did get moved around more than most, as I was always trying to find a place for it to make me like it more (sorry 'Black Dragon'). Good point about bacterial infection; I can't lower the humidity because of the fish tank (well, unless I run a dehumidifier which seems fruitless) but I did lower the heat a bit and I think I'll spray everything with some colloidal silver.

Thanks everyone for the insight!

I did notice that the Black Dragon was pretty sensitive to being in a humidity box and being sprayed on the first try (I'm sorry too, Black Dragon). I actually stopped spraying my Hoyas because some didn't like being sprayed, and others looked the same whether sprayed or not. And my room is not dry. This Dragon looks very good even after getting some leaves cut. I hope I won't mess up this time!

Black dragon is pretty standard, in care. I treat it like my other pubicalyx. It grows well for me.

I use an actual mister to mist my plants twice a day. The fine mist is easier on them (I think) than a spritz bottle or constant humidification via humidifier. I could be wrong about the humidifier, though. Never used one. Humid enough, here, lol.

Do you know what the RH is in your room/s, aurorawa? Mine is 70-80% and the only way I can control it is with ventilation. It's straight up Florida tropical in there.

Mine hovers between 60-80%. If I am not doing laundry, it hovers, on average, around 65%. If I am doing laundry, it can spike to 85%. The laundry room is through a door just to the left of my Red/Blue/White LED UFO. That door stays open on laundry days, closed the rest of the time. I control with fans. The ceiling fan, and two box fans that sit against the wall opposite my plant shelf. I usually only have the ceiling and one box fan on, but on laundry days, the other box fan goes on, as well.

Okay cool, I think I better add another fan. Can't wait for summer so I can actually open some windows and get some fresh air!

Last year when we were having those heat waves, I went outta town for a couple weeks. Came back to find my room had been over a 100* at 100% RH for dayyys on end. Lol that was a fun one to clean up.

I bet. I can't wait to shove these babies outside!

I use a sprayer with super fine mist. I think the problem I had was more with water beading up and staying on leaves of some sensitive ones. The Black Dragon didn't like it. Iris Marie doesn't like it either. Now when I spray, I make sure there's no drop of water staying on the leaves.

Tawny, maybe you can also put the more sensitive ones in less crowded area? The humidity of the microclimate of a crowded area may be higher than the rest of the room. Just a thought...

The raccoons can't wait either. JUST KIDDING!! :P

@themockturtle, I don't know what less crowded means, my room is stuffed to the gills, especially since a certain someone has caught the gardening bug and is attempting to propagate every.single.thing under the sun in there. Currently have 80,000 lemon grass starts if anyone needs some...

Lol, I feel ya. I'm currently looking at growing gingers. Together, we can make some Thai food.

Do it! They are super pretty and easy, that's one thing I don't mind in there. He's got turmeric going too, if I haven't mentioned that 14 times already. Lol

Wow, did you use the grocery store ginger?

Do you have coriander too? Then we can also do Indian.

Yes and yes and yassss. He even makes his own yogurt so we are all set for lassi & raita. :)
He's trying to start date palms from seed too. Hold me.

LOL I think he should grow some rice too. And some tea and coffee.

Lolz I have the fish for your paddies!

(Sorry Denise and aurorawa for blowing up your notifications)

Lol! I don't mind. I caught the ginger bug, as well! I have the standard food ginger, and a couple of those deliciously fragrant butterfly ginger. I also started growing citrus (moro blood orange, meyer lemon, persian lime, australian red finger lime, hirado pummelo and a nules clementine).