Aphids are about the size of a pinhead, may be almost clear, yellow, red, or other colors. You’ll find them on the growing points of everything from tomatoes to roses and should get them off asap. A blast of water will often take them down, and fortunately, they are very slow to climb back up. Since they feed and proliferate best on new growth, this step is sometimes enough. If it’s tiny vegetable transplants, however, it will be wise to follow up with a spray of WormWise Vermicompost Tea (that’s my choice), insecticidal soap or Neem, or a dust of pyrethrin. Even at this early stage, there are likely eggs yet to hatch, so the control should be repeated in 8 days. Yes, that’s how fast each generation comes to be, and if you do not get them under control, their numbers will increase geometrically to dehydrate your plants. No matter how much water you give them, their leaves will be compromised by the constant sucking of aphids and their friends, growth will slow or stop, and you’ll think tomatoes are hard to grow. They’re not! When it comes to insect control, remember Barney Fife’s words of caution “Nip it. Nip it in the bud.” Get to them early before they can get to your plants with serious damage.