There are a number of pests, including caterpillars, worms, moths and earwigs, that eat apricot leaves. Looking at the damage done to the leaf indicates what kind of insect is eating the leaves, according to SFGate.
If the leaf is full of holes between the veins, then tent or redhumped caterpillars, cankerworms or webworms are the culprits. The larvae of these insects feed on the soft tissue found between the veins of the leaves. The affected leaves can be removed.
If the edges of the leaves have been chewed, then western tussock moths, earwigs or citrus cutworms are to blame. The tree can be treated by spraying a strong stream of water to remove any caterpillars or eggs and then sprayed with a microbial insecticide.