The experts in these facilities have much experience . To submit samples to them, it is best to go through your county agricultural extension agent or lab instructor. Finding the insect is usually very helpful, but sometimes this is difficult to do. Some are very small and require very close inspection of the upper and lower leaf surfaces. Some burrow into the soil at the base of the plant when they are not feeding.
Some insects feed at night and can only be found by inspecting the plant at night.
Some insects are very mobile and can't be found because they have left the plant for new foraging grounds before their damage has been observed. The type of holes chewed into the plant, the location of the holes on a specific organ of the plant, feces and the types and positions of the spots caused by insects and mites can be useful in diagnosing which pest is involved. Collect as much information about the pest to help with its diagnosis. Each year we find a certain number of pests in our Hort 325 plots. Some, such as aphids, loopers, corn earworms, leafhoppers and stinkbugs appear every year.