Don't overpot in a pot that is too large. Remove and wash away the old potting medium. Examine the roots. Snip any rotten, decaying roots. Divide the plant if desired and place in a clean pot with fresh medium.
Insects are most active during the warm summer months.
Get into the habit of looking at your plants. Inspect the undersides as well. As temperatures increase, good air movement is important to your orchid plants. Healthy orchids are more resistant to pests and diseases. Remove dried sheathing on cattleyas to rid of hiding places for insects.