You don't need to tip them over, just flush the cups with your hose.

I had a whole bunch of larvae growing in one of my broms and no matter how many times I tried flushing the cup, they would come back, all the rain we were getting didn't help either. I eventually put some used coffee grounds in the cup and around the lower leaves that retain water late one evening and the following morning all the larvae were dead.

I got that tip from the "Bromeliads for the Contemporary Garden" book.

Here is a link that might be useful: Quote from Book

You can also add a few drops of very mild dish soap to a gallon of water and then pour some of it in the cup. This breaks the surface tension of the water so that the larvae drown. Just don't squirt a bunch of it directly in the cup. It doesn't take much.

I've even tried putting some broken chunks of mosquito dunks in there. Worked till the rain washed them away.
Tally HO!

I've used the crumbled up mosquito dunks with good success as well! They give decent control for several weeks at a time.
Paul

There is a microbial insecticide, 'bacillus thuringiensis' that can be sprayed on plants for the control of insect larvae. I believe a formula has been developed for larvae of flying insects, i.e. mosquitoes. This may be what is in the mosquito dunks.

Can someone tell me what mosquito larvae looks like? Thanks, in advance

Nana

Nana, check the link (it may take some time to load).

Here is a link that might be useful: Mosquito larvae video

get a magnifying glass and look into a pool of standing water you can see them

Here is a link that might be useful:

I think mosquito dunks use the bacteria you mentioned.

Try a drop of vegetable oil in each "cup'.