Aphids suck plant juices and are usually found at the stem tips. A heavy infestation will coat the leaves with sticky honeydew. A black, sooty mold can grow on the honeydew. The insects can be green, white, pink or black.
Scales are usually brown, hard shells attached to the stems or undersides of the leaves. Sprays are not effective since the shell protects the insects. Heavily infested plants should be discarded. Physically removing the scales and then controlling immature stages with sprays may control the problem on lightly infested plants.
The orchid weevil is about 1/8 inch long, smooth, and shiny black. The larva is a white legless grub about 1/16 inch long. The larva feeds on the new roots, hollowing out the inside. The tips of infested roots turn black. The adult feeds on the roots and tender young leaves, sheaths and bulbs. The adult may feed on flower petals before they open. Injury caused by the insect may be entrances for diseases.
Slugs feed on buds, blossoms, leaves, and tender stems.