I have a couple plants that are close to harvest. Bubblegum auto & Jack Herer auto. I dont see trichomes getting cloudy just yet on either.
Today I noticed Bubblegum is browning on the very top. Otherwise it looks good. We had a heat wave recently, but cooler the last few days. Hot today though.
Next to it is Jack Herer which, I believe, has some aphids. I hear lady bugs might be good for that, but I’m most concerned with the browning one. No nutes for the last week.
If that is an outdoor grow then it’s either bud rot (un smokable) or it could be either spider mites or a Caterpillar.
Look inside the bud closely, with a magnifying glass and look for mold or rot. Does the brown bud seem really dry or crumble when you touch it?
You may need to harvest it now to save what you have if its bud rot or mold.
Yes @Rye is correct. Any part of the flower that looks like that is sign of a problem which needs to be investigated immediately. A jewelers loupe or magnifying glass will be most helpful determining the root cause.
Today this top had a small dead patch which at first appears to be bud rot an inch or so below the top. If left unchecked the whole top would be gone in a matter of days. Don’t be afraid to pull or cut it off (it may come off quite easily) and dig around with some tweezers. You are looking for anything that looks abnormal 
I was able to easily pull the top off. It’s somewhat crumbly. Then I found a little Caterpillar right under where the bud was.
Also, thanks for the help. I recently bought a loupe and am learning what to look for. I think I could have caught the aphids quicker…
Yes, I learned this the hard way too. It’s my first grow so I had no idea what to expect (except the unexpected) lol. Try to pull as much of the dead material and poop as you can, you may find a tunnel or hole the larva creates, if so follow it. If it’s too extensive try to remove the damaged bud from the main stem and search around the area.
If you found 1 assume there are more. Keep checking and removing any dead material as necessary, that will help keep the wound from turning to rot.
I am spraying with BTK but @kmac03 posted a recipe for a home made concoction of hot peppers and garlic… Check this thread for details Caterpillars ate my flowers
UV Black light at night will make the tittle buggers glow at night but difficult to see if they have burrowed deep inside. Hope this helps, good luck to you!
Totally off topic, but every time I see “Caterpillars ate my flowers,” I hear, “The dingo ate my baby!” (From a news story long ago)
Apologies. Carry on. 
Wow…go you for catching it. So many don’t follow their intuition. No other evidence of others?
@Treefrog4443 glad you caught it. Look for more. You can use row covers to cover your plants while still allowing light, air and water to freely pass. The blacklight flashlight works. Search your buds at night, carefully, slightly pulling them open. Make sure theres no other lights on. The white stripes and spots on the caterpillars glow brightly.
During the daytime look out for any small blue, light blue, or white butterfly’s on your plants. Those are actually in the cabbage looper family. I plant trap crops and use BT to control them.
