Recently, rapid emergence of weeds thought to be resistant to Roundup have been observed. Horseweed, giant ragweed and pigweed, among others have been found growing with crops across the United States.[6][7][8] Insects including corn rootworm and bollworm have also begun showing signs of resistance.[9][10][11][12] In response, Monsanto has continued to develop new products.[13][14] The USDA approves use of Bt crops.[15] Monsanto has denied there is a problem with their product.[16]