Is there a way to tell if fruit flies have laid eggs?

Question

I am going cross-eyed trying to tell if there are fruit fly larvae on the walls of my continuous brew kombucha. I have seen fruit flies on the outside, but I don't think they can get in through the two towels and rubber band sealing the top.

I assumed that the specks I saw on the walls were just bits of tea and bubbles, but after doing some research I got a little paranoid. I set a trap to deter fruit flies so I'm not worried about more (if any) infiltration, but how can I know if there are fruit flies inside? Would I just have to wait for them to mature and see if I have fruit flies buzzing around inside after some amount of time?

The scoby is seen at the bottom of the picture. There is a distinct line of bubbles. That isn't what I'm worried about; that's normal. What I am concerned with is the specks stuck to the wall that aren't touching the scoby.

Answer 1

Fruit fly eggs are yellow 1/2mm long and will generally hatch into larvae in ~30Hours, so if they are still there 2 days later then they are specks of stuff, if the hatch then they are larvae, which will likely fall into the liquid and drown. I hope that helps you.

Edit:

Oh, also CO2 tend to put the fruit flies to sleep, so if they were to fly into the bag the CO2 from the SCOBY would likely hit them before the laid any eggs, and is likely to drive them away from crawling under the edges of your towel.