Some insects cannot be reared, or it is very expensive to do so. For these, the best place to test a product is the field, which also presents reality, so that you can be sure that if a product works in field, it really works. But field tests are never easy and even a slight change in conditions (wind, sunshine, variations in humidity or temperature, the time of the day and so on) may strongly affect results. Field tests, however, are still the only completely reliable protocol for testing ambient repellents for outdoor use.
