Insects are both highly attracted to UVA and UVB. Different insect orders may have a preference for one or the other, likely both in the case of Hymenoptera. (which includes ants) LED black lights rarely emit UV below 380 nanometers which excludes the UVB spectrum, making them less than ideal choices for insect lures.
Your average black light is simply a low wattage fluorescent bulb tailored for mostly UVA and some UVB production with a coating to block out most visible light. The black lights used for insect attractants are essentially the same save for the fact that the coating is omitted to allow for some visible light, which in itself also acts as a lure. Many lights emit UV radiation, not just black lights. The most common lights that do includes - from least to most powerful - fluorescents, CFLs, and mecury vapor/metal halides. Higher wattage CFLs (the bulb I linked to) will emit high amounts of both UVA and UVB, and within the correct color spectrum 6500k-7500k they may be more effective due to the increased amount of light, which acts to call in insects from a distance. MV/MH bulbs are similiar, but overall much more powerful and hotter.
Edited by 123LordOfAnts123, June 13 2017 - 11:10 AM.