Suffering from an infestation of Cimex Lemicularis (AKA the Bedbug)? This ancient scourge of human sleepers has made a massive resurgence in some places in the US and Europe (and the rest of the world) in recent decades. This is mostly because it is no longer kept in check by pesticides. DDT, the most effective at controlling them, is now illegal to use in most of the world, and the critters are mostly tolerant and resistant to the pyrethrins that are the most used "over the counter" insecticides in the Americas.
A report out of Penn State in 2012 reports that a biological control agent in current use - Beauveria bassiana, a soil derived fungus - has some (!) effectiveness against C.Lemicularis. The insecticide is actually one of the more benign products available (there is a certified for "organic" use version) even though the MSDSs (Material Safety Data Sheets) carry all the familiar insecticide warnings.
It is a highly tempting prospect to get some of the product and see if if works against ones own infestations, but the way the laws for pesticides in the US work, it is illegal to do that outside of an accredited research laboratory. [There is some anecdotal evidence from folks who have done so anyway.]
Meanwhile, we suffer along, waiting for a truly effective anti-bedbug product to be developed.
Beauveria bassiana is an interesting fungus. It occurs worldwide in various soil conditions and is one of the "clean-up" organisms that remove insect bodies from the environment. The spores come in contact with an insects chitinous cuticle and secrete an enzyme that penetrates the shell. It then grows on the inner flesh of the insect, and completes the cycle by forming sporing bodies on the cadaver.
It is approved for use on aphids, thrips, white fly and certain other insect pests, and in the organic formulation, may be used to protect organic produce from these pests in a "certified organic" manner. In the Penn State report it seems clear that they were using the organic formulation - talking about oil with and without spores in suspension - and the use of an airbrush applicator. Apparently the bedbugs pick up the fungus and carry it back to their "harborages" (nests) before succumbing (at >90% effectiveness) to the fungus which will then attack and kill the other bedbugs in the group.
If it can be shown that bedbugs cannot develop an immunity to the fungus, it may be that the old adage: "Sleep tight and don't let the bedbugs bite" will once again become a legendary warning.