What Is the Best Insecticide to Use to Kill Bugs on Cucumbers & Melons?

Common Pests of Cucumbers and Melons

• Being in the same family, cucumbers and melons share many of the same pests, including cucumber beetles, spider mites, whiteflies, squash bugs, melon aphids and pickleworms. Cucumber beetles eat holes in leaves and cause them to wilt. Spider mites create pale flecks on leaves along with fine webbing underneath the leaves. Leaves under attack by whiteflies will turn yellow or end up with a sticky film on them that can grow black mold. Squash bugs can do considerable damage in the form of leaves with pale-to-brown blotches and shoots that blacken and die back. Melon aphids cause curling and distortion of the leaves, and pickleworms tunnel into flowers, buds, stems and fruits.

Chemical Insecticides

• A number of insecticides are effective against most cucumber and melon pests. Clemson Cooperative Extension recommends using pesticides containing permethrin, bifenthrin or esfenvalerate for cucumber beetles, squash bugs and pickleworms. Permethrin should be applied at 6.4 to 12.8 ounces per acre, bifenthrin at 2.6 to 6.4 ounces per acre, and esfenvalerate at 5.8 to 9.6 ounces per acre. Acetamiprid takes care of most common pests except spider mites. Apply it at 2.5 to 5.3 ounces per acre. If spider mites are your main problem, abamectin or bifenazate should do the job. Apply abamectin at 8 to 16 ounces per acre and bifenazate at 0.75 to 1.0 pounds per acre. Wait three days after spraying to harvest the fruit when using any of these insecticides.

Natural Insecticides

• Rotenone, applied at 1 to 2 pints per acre, is a natural pesticide that may be used safely on both cucumbers and melons for young squash bugs. Natural biodegradable soap spray mixed with peppermint oil or citronella oil is an effective control for all of the pests that plague both the cucumber and melon plant except for pickleworms. Use 4 to 5 drops of oil per gallon of soapy water. Spray directly on the insects. A dash of hot pepper sauce adds to the effectiveness. Coconut oil may also be added. Coconut oil suffocates most insects. For pickleworms, Bacillus thurigiensis, or BT, is the most effective. Apply BT at 0.5 to 2.0 pounds per acre.

Biological Controls

• Biological controls can be a viable alternative to insecticides for some of the insects pestering your cucumbers and melons. Lady beetles, lacewings and the larvae of syrphid flies feed on melon aphids. Likewise, whitefly nymphs may be eaten by lady beetles, lacewings and parasitic wasps. Nematodes (Steinernema carpocapsae) may be used to control the pickleworm, although they are not as effective on cucumbers and cantaloupes. Predatory mites, lady beetles and minute pirate bugs will feed on spider mites. Do not use biological controls if you are going to be using insecticides as well.