I have had a few grasshoppers eating the petals of my dahlias. Maybe its them? I kill them when I see them.

Sounds like earwig damage. Steve in Stevens County.

I agree with oscarthecat it is like European earwig damage. I have a way of killing them, but it attracts rats! Had to stop using it. But growing dahlias anyway. Killing these pest by hand is tedious and they are difficult to get at. Anyone know how to really do a good job with the the earwigs? maxcy

If it is earwigs, you won't see them because they hide during the day. You can go out with a flashlight at around 10pm and see what is in your flowers. It could be earwigs or maybe Japanese Beetles. If its earwigs, cut a slit in an old tennis ball and place it on top of the stake the dahlia is tied to. The earwigs hide in there to escape the sun during the day and you can shake them out and smash them. Yuck. But it works pretty well. I've read on the forum somewhere that some people use a bait made out of soy sauce. Type earwigs into the search bar and you'll find all kinds of info. If its Japanese Beetles I have no good advice. They are horrible and I don't think any spray or poison really works. I go out at night and pick them off and throw them in a bucket to drown. Every night I kill hundreds and it doesn't seem to make a dent in the party the next night :-( BTW, you can't drown earwigs, they climb out of the bucket and right back into your flowers.

I agree Jennifer. Should have mentioned it in my previous comment. Occasionally I see them during the day tucked in new leaves on our hydrangeas. Before I discover the rats I would do as you do and go out with a flashlight and a tall plastic jug with a small amount of the soapy water. Got hundreds from my small dahlia area. When I discovered the soya sauce and cooking oil method it did a better job than my picking. But then the rats came and would tip over my bait stations. Had to get rid of the stations and the rats. Now I use a form of white powder that is supposed to cut the earwigs causing them to die. Doesn't seem to work too well for me. I try to focus on the flowers and ignore some of the chewed leaves, but the flowers are also susceptible, especially as they begin to fade. No more bait stations, flashlights and soapy water for me. My dahlias are blooming well and their flowers look great, but I know the earwigs are there. Ugh! Anyone know what to do to attract earwigs only? Maxyck

The best time to fight earwigs is in the spring and early summer, when you just plant out the dahlias. There is an ant/earwig bait that you can sprinkle around the bed, and it cuts down on the population before they have a chance to build up. If you google 'earwig life cycle,' you'll see that they create dens to raise their young. Once they have grown and climbed up the dahlias, only chemicals that kill bees remain an option, other then setting up hiding traps and manually eliminating them.

Yes... I finally discovered caterpillars on the back side of the petal, but really hard to find. They devour the petal like a huge chopping machine and slender & only 3/4 inch long. Head was a slight yellow while rest was a light green. Did not identify the type of caterpillars but did not eat stalk and hardly any leaves...only the beautiful PETALS from outside edge toward the center. At fisrt thought it was a snail that went back to ground during the day but no tell tail slime trail & no snails found anywhere around the plants base. Finally found the caterpillars on the 3rd day when the flower petals were almost gone on the back side of the petals.

Diatomaceous Earth works very well but you need to sprinkle it around every few days. It’s amazing. But I’m going to spray the plant with neem oil, then sprinkle cayenne pepper at the base leaves and put out snail bait too.