Fruit trees such as the orange tree are often prey to insects. They have lost their natural immunity due to cross-pollination. You'll need to get an industrial bug spray, make sure it is water soluable so it washes off the fruit.
The aphids and mealy bugs are the main enemy of the orange trees. They are popularly known as bronze orange bugs. If not treated well it will kill the tree later. We can avoid them by spraying and rinsing the stem and leaves.
It's best to spray the tree with water to remove aphids or mealy bugs, and to hand scrub the leaves to remove the sappy substance excreted by the bugs.
The common remedy for bugs on an orange tree is aerial spraying of an insecticide, the type of the insecticide determined by the type of bugs that are on the orange trees.
