A packaged chemical heat pad 100 for an insect trap 10. The heat pad 120 comprises an air tight protective packaging 110 surrounding the chemical heat pad 120. The chemical heat pad 120 comprises a semi-permeable membrane 130 which is filled with chemicals 140, which on activation by oxygen, following the removal of the protective packaging generate infrared heat and water vapour. The pad will, over at least an 8 hour operating span, maintain a pad surface temperature at between 20°C and 40°C and a relative humidity at least 10% higher than the prevailing humidity. The pad is used within an insect trap to mimic the characteristics of mammalian bodies and is used in particular to attract bed bugs.
