From the photograph you sent in, it looks like an insect is seriously attacking the leaves of your daphne plant! This is rather unusual as the leaf of the Daphne is quite thick and not as attractive to insects as many other plants. 

To identify the "culprit”, head outside at night with a torch, and you will be surprised at the amount of activity in the garden after hours. If you are unable to identify the insect, catch a specimen in a bottle and take it to your local garden centre. 

To maintain healthy Daphne bushes, add Garden Time™ Compost to the existing soil regularly and ensure that the plant is kept moist in summer, and not too wet in winter. 

When available purchase Daphne odora rubra, as opposed to Daphne Leucanthe, as the odora rubra plant has a better form and flowers more prolifically.