We have these small worms inside our coreopsis buds eating them from the inside. Have had coreopsis for many years and have never had a problem with pests. Can you tell us what to do about them?
Bud Worms in Coreopsis
Certified GKH Gardening Expert
This article should help, though it's directed to roses it would still apply to your situation as well: https://www.gardeningknowhow.com/ornamental/flowers/roses/budworms-roses.htm
If it is not budworms but another caterpillar or worm pest attacking your plant, then they can be treated with products containing Bacillus thuringiensis (Bt), a natural bacteria that kill worms without harming plants. Neem oil may be helpful as well. Here is more information: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/using-bacillus-thuringiensis.htm