I recently built a new experiment tank for my bed bugs. I purchased two slippery plastic tubs from Walmart – one large one and one medium one. I rubbed baby powder onto the insides of the plastic tubs to make them slippery. Then I put two inches of mineral oil on the bottom of the largest tub, put a concrete block in the tub, and then placed the smaller tub onto the concrete block. That way any bugs that escaped the smaller experiment tub would fall into the mineral oil. If the bugs could swim they would have to climb the slippery plastic of the larger tub. Pretty safe construction. The floor of the experiment pan was made of 1/8 inch brown hardboard which was varnished to simulate a hardwood floor. It is a nice piece of equipment.
I placed the tank beside my existing experiment apparatus (I want to keep that one also) and started my experiments comparing the efficacy of different traps. But I found that most of the bugs went to the north side of the tank making my experiments unfair. So I flipped the tank around and the bugs then migrated back to the north side. Hmmmm. I then noticed the light was at a 10 degree angle from top dead center of the tank. I theorized that the bugs were sensitive enough to light to always walk away from the light – even if it is only a 10 degree difference.
So I put two traps of each kind into the tank in a diagonal pattern so that both styles of traps would have equal numbers of bugs in the vicinity. Because I now had four points I put a table above the experiment with each leg resting on one trap. I could then put the Co2 source onto the table. But now one corner of the tank had more shade from the table. And my traps showed the bugs tended to be caught in the shadier spots. Once again my experiment was unfair.
So I built a shade on top of the tank to make all portions of the tank equally shaded. Now my experiments show a good balance of where the bugs are caught – excellent.
I learned that bed bugs can sense a 10 degree slope of light and move away from the light and that any dappling of shade/light plays havoc with the experiments.