Walla Walla farmers built salted bee beds that house 18 million native alkali bees

The dry Walla Walla Valley on the Washington-Oregon line has little summer water, so most of its 22,504 acres grow alfalfa seed rotated with wheat, which need none. The families who farm it produce about a quarter of the US alfalfa seed. Honey bees pollinate it poorly because they dodge the flower's stamen strike and steal nectar from the side.

Elsewhere growers buy Canadian leafcutter bees, which are costly. In the 1950s one researcher noticed that native alkali bees pollinate alfalfa very well and began working with farmers. The bees nest in salty, moist soil, so growers tried ditches and rock-and-straw trenches and finally a system of pumps and underground perforated PVC pipes covered in tons of table salt.

Growers also changed their pesticide use. With a Washington State University entomologist they spray only when harmful insects outnumber beneficial ones by a set ratio, choose less toxic products, and spray at night while the bees sleep in their holes.

Build the nesting habitat for a wild specialist pollinator, so you get it free and in numbers instead of renting bees.

The bees range 3 to 5 miles per trip and trip the alfalfa flower properly.

Native bees nest in the ground, so soil moisture and salt could be engineered cheaply.

Neighbors share the benefit because bees ignore property lines, so growers cooperate.

Night spraying and ratio-based thresholds cut die-offs from pesticides.

When a free native specialist does the job better than a bought-in generalist, invest in its habitat and protect it from your own operations.

NPR reported in 2018 that the valley's beds hold about 18 million bees, built at a cost of thousands of dollars per acre. A WSU entomologist said yields per acre are 50 percent greater than anywhere else alfalfa seed is produced in the western US. Seed sells for about $42 million per the state agriculture department. Past die-offs came from heavy rains and pesticides, and a county speed limit protects bee areas.