To many entomologists, trees like oak, birch and willow are top trees as many invertebrates feed on the foliage of the leaves. Other trees such as lime and ash have fewer invertebrates associated with them.
Holly, Ilex aquifolium is a tree of which the leaves are eaten by relatively few insects. However, holly is a valuable tree for the wildlife garden for other reasons. Holly has male and female flowers borne on separate plants which is called dioecious.
It is a tree which sometimes flowers a lot while other trees nearby show hardly any flower. In my garden, the male tree is always full of flowers and the female tree nearby has fewer flowers. The flowers though are rich in nectar and pollen is also collected. Honeybees, bumblebees and several species of solitary bee can be seen foraging on this plant.
The tree provides cover for birds and the dead leaves decay slowly and the dry leaf litter can be a shelter for amphibians. The berries are eaten by thrushes such as the redwing, Turdus iliacus.
The flower buds are food for the caterpillar of the holly blue butterfly.