Answer: I'm surprised that you have aphids in the midst of summer heat, as they are considered a cool-season pest in the low desert. It's really important to identify exactly what is eating your plants before attempting to spray something on them. Are you certain they are aphids and not perhaps whitefly immatures, which are more common now? However, ants do "herd" aphids, protecting them from predators in exchange for honeydew, the sweet excrement the aphids produce.
I always start with the simplest method first, and if that isn't successful, move on from there. Aphids tend to congregate on the tender new growth, and are easy to squish in large groups, using fingers or a paper towel. You can control them by blasting them off the plants with a strong spray of water daily (either early morning or late afternoon, when plants are not in direct sun), making sure you get underneath and between leaves where the aphids may be lurking. Because they reproduce rapidly, a one-time shot is unlikely to control them. The insecticidal soaps are made from plant-derived fatty acids and target soft-bodied insects. There's really no way you can target the bad guys without fallout on the good guys, i.e., the beneficial insects that will consume aphids. If you can regularly monitor and tolerate some damage to your plants, over time Mother Nature strikes a balance, with the beneficials and birds coming in to eat pests. Healthy vigorous plants will withstand insect attacks best, and it's really the best thing you can do to provent long-term insect problems. Make sure your veggies aren't stressed for water and nutrients.
Beneficials often arrive a week or two after the pests, so not spraying with insecticides is a good idea if you'd like to attract them to your garden to consume aphids for you. Good luck!
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