Wilted, Dried-up Leaves Caused By Squash Bugs. The leaves on cucumbers infected with squash bugs wilt, dry up, and turn black. If not controlled, the entire plant will die. Adult squash bugs are flat-backed, shield-shaped, brown to black, with a light-colored outline on their abdomens. They are 1/2 to 3/4 inch long and lay brown or red shiny eggs on the undersides of leaves. Adults and nymphs suck juices from leaves, causing them to wilt and dry up. To control these pests, spray plants with insecticidal soap every 2 to 3 days for 2 weeks. If this doesn't work, dust the plants once with rotenone. Dust the plants once more if it rains. Always read and follow label instructions no matter which insecticide you choose.
You can also protect the plants by covering them with a barrier such as floating row cover. Remove the barrier when plants begin to bloom.
Neem Oil Soap will kill Squash Bugs. Go to Yardener's Tool Shed to check out Bonide\'s Bon-Neem