Control the corn earworm, Heliothis zea, organically by rubbing or spraying the tops of the corn cobs where the worm larvae eat the silk with corn or mineral oil to create a blockade that the larvae cannot pass. Do this about when the silk is about a week old. Cut off infected parts of the corn cob if the worms have moved to the kernels. Use other insects, such as lacewings or pirate insects, to kill the worms. Spray the crop with neem oil to kill the worms.
Kill corn aphids by spraying them with a mixture of a gallon of water and 4 oz. of an extract made from hot peppers, wax, eucalyptus, garlic, onion and other spices. Be sure to spray everywhere the aphids are so the capsaicin from the peppers will get absorbed into the aphids' skin and kill them. Try a concentrated garlic solution mixed with water to form a barrier to protect the corn plants. Spray the plants so the garlic goes through the plants' pores and makes the plants unpalatable to the aphids.
Use natural predators such as ladybugs, beetles or praying mantises to hunt and kill insects. Encourage birds to prey on insects by placing perches or birdhouses in or near the corn crop. Do not spray pesticides--they will kill off good insects as well as the bad ones.
Get rid of the European corn borer caterpillars by pulling out and disposing of infected corn plants. Do not leave the pulled stalks to lie on the ground--the larvae or eggs will survive. Pick off individual borers by hand in very small corn gardens. Break open the stalk near any holes you see and pull the worm out. Buy ladybugs and release them into the cornfield to prey on the eggs.
Spray only natural and organic pesticides on corn plants. Ask at your local gardening supply store which brands work best for the particular insect you need to kill. Several methods can be used in integrated pest management, or IPM, to kill problem insects and then prevent them from returning. Decide which method or method you need and be vigilant. Monitor the plants for signs of infestation.