Yes there are indeed worms in blackberries and there have been for years.
The worms that are in blackberries are not harmful to your health but you can open the blackberries and remove them first if you prefer.
I've eaten several blackberries for years without even realizing or knowing that the blackberries contained worms.
Some of the blackberries may not contain worms but the majority of the blackberries do contain worms.
You can also remove the worms from blackberries by filling a sink or large bowl full of ice water, and add about 2 Tbsp to 1/4 c. salt.
Dump the fresh blackberries in, and allow them to sit for about 10 min and then gently swish them around to help loosen any die hard worms.
The worms in blackberries are called Drosophila suzukii.