Indirect Problems (cont'd) Insect resistance: -insects adapted -had thicker skins -transformed poison Pest population increased: -killed natural predators		Finally, DDT lost its powerful effect. Over time, many insect pests could no longer be controlled by DDT. Insects adapted or became resistant to the poison. Some types of insects survived chemical spraying because they had thicker skins. Others became immune to DDT because their bodies could transform the poison into a harmless chemical. Some pest populations actually increased after the use of DDT. This occurred because the pests had no natural predators left to control them. DDT spraying had eliminated the birds and animals that used to prey on pests in the treated area.