Not required. Insect nets can be expensive, so a lightweight fishing net with small holes also works well (and is a lot cheaper). A fish landing net is cheaper ($20+) whereas a dedicated insect collection net can go for $50 or higher for the more Odonata centric models. Fish landing nets can be acquired from your local outdoors store or even large box supermarket. Insect nets can be ordered from Bioquip or Rose Entomology. If you are only planning on collecting dragonflies and damselflies, I recommend going for the cheaper and easier to acquire option.