That's unusual. Please, post photos.

The small holes look like slug or snail damage but I don't know about the other damage. If these cannas are an expensive variety with fancy flowers, it might be worthwhile investing in pesticides. Otherwise, I agree that you should get rid of them.

You do not
provide your location but I am 99% sure your cannas are infected with the
lesser canna leaf-roller. Almost everyone living in the southern areas of the
United States learn to easily deal with this problem with only moderate
expense.

If you make
timely applications of a good systemic
insecticide that contains “acephate”, you will get excellent control. Applications
typically are applied at 3 to 4 weeks intervals; please follow the label
directions.

I personally
prefer Orthene 97 Spray but there are other choices. Applications are best if
started early in the season prior to infection but are still effective. Just
remember to make follow up applications.

I do not see
any other major problems with your cannas but you might consider thinning them
out.

Kent

Also for any other bug issues, sometimes you can buy a concentrated container of insecticide, a 1 gallon sprayer, and then mix it yourself and use with the sprayer. Saves a lot compared to buying a ready-to-spray version.

"Orthene 97 Spray"

I am impressed by how inexpensive that is. See

http://www.ebay.com/itm/like/251875593222?lpid=82&chn=ps&ul_noapp=true

And, for the OP's sake, I should mention that good 1 gallon sprayers can be bought for as little as $5. I recently bought three at Aldi.

Sometimes I just cut them to the ground, thin them out a little and that rejuvenates them