Q&A: Cucumber Beetles
Q: How can I get rid of cucumber beetles without harming my other vegetables and also prevent them from returning?
A: First of all, make sure your plants have the correct growing conditions — full sun, plenty of moisture at the root zone and deep, rich soil. Trellises keep plants and fruit off the ground, too. You can protect your cucumbers with a fabric row cover to keep flying insects such as cucumber beetles away from the plants. Install the covers when the plants are still small. If you pin the fabric tightly to the soil, that should also deter most "crawlers" like slugs and squash beetles. Put the covers in place when the plants are still small. It's important to check under the cover frequently, though, for other pests, such as aphids.
You can keep your cukes undercover if you grow parthenocarpic varieties. These don't require pollination to set fruit, so you don't have to remove the cover when the plants blossom to allow pollinators access. Try such varieties as 'Burpless' or 'Sweet Success'.
Cucumber beetles do the most damage not by what they eat but by what they spread. They're known to carry the bacterium that causes bacteria wilt, a very serious disease of cucurbit crops. There are two types of cucumber beetles — striped and spotted — and the striped beetle is usually blamed for the disease spread. Natural predators of the cucumber beetle include tachinid flies, braconid wasps and soldier beetles.
Hope this information helps!