It is usually very apparent if winter moth caterpillars have invaded your garden or greenhouse, with large chunks often missing from the leaves of trees.
New leaves are also usually bound together with silk threads and tend to be partially eaten by the insects, the Royal Horticultural Society (RHS) reported.
They can also damage developing fruitlets and blossoms, with apples showing deep clefts by the time they are fully grown.
The damage is most notable in summer when leaves are fully expanded and the holes created in spring have grown with the tree.
While apple, pear, plum and cherry trees are particularly at risk, ornamental trees such as oak, sycamore, hornbeam, hawthorns and hazels are also vulnerable.
To deal with the problem, garden and greenhouse fans should invest in a greasy band to place around the trunk in late autumn, which helps reduce egg-laying.
This can be bought from most gardening centres, which should also supply deltamethrin or lambda cyhalothrin for those who wish to go down the chemical route.
Meanwhile, the RHS has revealed that introducing garden and greenhouse activities to kids with special educational needs helps to get them more involved in group work.