Dee Patel, an entomologist, told BBC Three Counties Radio that lavender deterred bed bugs.

“Lavender oil masks their scent pattern and they can’t cope with it,” he said.

I don’t know about their scent pattern, but that’s an essential oil.

Maybe mix it with an insecticide.

https://www.purdue.edu/newsroom/releases/2021/Q2/essential-oils-restore-insecticide-effectiveness-against-bed-bugs.html

Essential oils restore insecticide effectiveness against bed bugs

Gaire and Gondhalekar first tested the pyrethroid insecticide deltamethrin and a series of essential oil compounds on non-resistant bed bugs and a resistant Knoxville strain of bed bugs. A single dose of deltamethrin meant to kill 25% of bugs killed that many non-resistant bed bugs, but it took 70,000 times more to kill 25% of the Knoxville strain.

“Deltamethrin is so ineffective in the Knoxville strain of bed bugs that if you’re using it in the field even in large doses, you’ll get almost no control,” Gaire said.

The active ingredients in essential oils — thymol from thyme, carvacrol from oregano and thyme, eugenol from clove, and others — worked equally against resistant and non-resistant bugs. A dose meant to kill 25% killed that many of each type.

Gondhalekar said bugs’ nervous systems normally open and close sodium channels to pass signals through neurons. Deltamethrin binds to those sodium channels and keeps them open so that neurons cannot stop firing. That repeated firing quickly uses up the bug’s energy and kills it.

But resistant bed bugs possess multiple mechanisms to resist pyrethroids, including overactive levels of an enzyme called cytochrome P450, which degrades deltamethrin. The essential oil compounds, Gaire and Gondhalekar reported, bind to and deactivate that enzyme and allow deltamethrin to do its job on the bed bug’s nervous system.

Gaire and Gondhalekar combined a single dose of deltamethrin with a single dose of essential oil compounds that would be expected to kill 25 percent to 50 percent of the resistant bed bugs. Instead, it killed more than 90 percent of the resistant bed bugs.