Although swiss chard (also known as beet leaves and silverbeet) seems to be like lettuce, it is more infested than most lettuce and more difficult to check.
Consequently, one may discard the leaves and eat the stalk.
Or, one may wash and check the leaves as below:
How to Check Swiss Chard for Bugs
1. Remove each leaf from the head.
2. Soak the leaves in a solution of vegetable wash and water. Enough vegetable wash should be used to make the solution feel slippery and sudsy. The solution should be in a vessel that is large enough to fit the product to be checked, and to allow an individual to vigorously agitate the product.
3. Agitate the product in the solution.
4. Remove the product from the solution. Direct a stream of water at each leaf, on both sides, and rub the leaves with your fingers during the process.
5. Check both sides of every leaf, using a light box.
It should be noted that swiss chard may have folds that make checking difficult. For the checking to be effective, one must be confident that one has thoroughly checked all parts of the leaf.