I had the same problem with my apricote and peach tree. The leaves curled up and were very deformed. I was told it wasn't bugs but a virus. I questioned what causes this and I was told that the virus is airborn and your plants can get it just from the wind blowing across the yard.
I was told the only thing you could do was to spray the plant with a solution that can be bought at Canadian Tire for Leaf Curl and you spray only in early spring before the buds start forming. They have a book in the garden centre showing leaf curl and it tells you what to spray on it and they sell the product you need for this.