Half of winning the war against garden bugs is knowing what type of pest you are dealing with. The most common yellow and black striped bugs to be found crawling over the leaves or across the fruits of zucchini, cucumbers, squash, beans, melons, sweet potatoes and corn plants are cucumber beetles.
The cucumber beetle is an oblong, oval-shaped bug approximately ¼ inch in length. Their yellow-green shells bear three, straight black stripes that run lengthwise down the lower portion of the body. Additionally, the center segment of the back leg is yellow, rather than black. There are some cucumber beetles that bear a series of black spots, rather than stripes, on their shell.
Adult cucumber beetles eat the foliage, fruits and flowers of vegetables and other garden plants. They lay eggs on the undersides of plant leaves; once the eggs hatch, the larvae burrow underground and feed on the roots, stunting the plant's growth. Additionally, both the adult beetles and the larvae carry bacterial wilt and mosaic virus -- plant diseases that can be lethal to a garden. The bacteria that cause these disorders lies dormant in the bodies of the beetles during their winter hibernation, only to be reactivated by warm weather. The live bacteria are then transmitted from the beetle to the plant via the insect's feces.
Prevent cucumber beetle infestations by practicing good garden sanitation to eliminate potential overwintering sites. Surround vulnerable plants with a thick layer of mulch as this inhibits the ability of the beetle to burrow beneath the soil; replace the mulching materials each spring, effectively removing any contaminated materials. Protect seedlings with floating row covers; these sheets of thin plastic keep the insects from landing on the leaves of the young plants. Remove any visible beetles by hand, plucking them from the foliage and dropping them into a bucket filled with soapy water. Spray plants weekly with a rotenone- or malathion-based insecticide or dust the leaves with an all-purpose bug repellent as a preventative measure.
To control pests without using harsh chemicals, include a variety of flowering plants in the garden’s design. Flowers such as marigolds, beebalm and zinnias encourage the presence of beneficial insects that prey on harmful bugs. Also, susceptible plants can be surrounded with radishes; the scent of the radish plant is naturally repellent to many bugs, including the cucumber beetle. Should an infestation occur, spray affected plants with a homemade insect repellent made from adding 6 tsp. of cayenne pepper and 1/2 tsp. of dish washing soap to 1 gallon of water. Thoroughly coat both sides of the leaves as beetles tend to hide beneath the foliage.