The Clemson Cooperative Extension notes that cucumber beetles, spider mites, melon aphids, squash bugs, squash vine borers, pickle worms and squash beetles do the most damage to cucurbits like cucumbers. Of these, squash vine borers and pickle worms are the most obvious grublike creatures.
Symptoms of cucumber pest infestations include the presence of the grubs themselves, wilting and death of plants and fruit, droppings from the grubs and holes in the stems. Most grubs bore into the stems, fruit and buds of the plants and devour the plant matter inside.
The Clemson Cooperative Extension suggests planting pest-resistant cucumber cultivars and quick-maturing varieties, which grow and bear their fruit before insects become a problem. Control existing infestations with pesticides such as insecticidal soaps or neem oil. Use the pesticide at night to kill the grubs without killing bees or butterflies.
The best prevention for pests and diseases is a strong offense of healthy, thriving cucumber plants. Strong plants are not immune to problems, but they withstand them better than weak plants do. Put cucumbers in sites with full sun and quick drainage for best growth and warmth, and amend the soil with organic compost at planting for nutrition. Put cucumbers on trellises to restrict their contact with soil.