It is notable as the only insect that is known to feed exclusively on a plant which hyperaccumulates nickel, specifically the milkwort jewelflower Streptanthus polygaloides.

[1] In turn nickel accumulates in the cell tissues of M. boydi offering it partial protection from predators in its environment.

This excess metal is of some benefit to the plant as it makes it toxic to many generalist insect herbivores as well as various pathogens.

[2] However M. boydi not only tolerates the high nickel concentration in the leaves of S. polygaloides but feeds exclusively on this plant at both larval and adult stages.

Subsequent lab experiments found that a diet of M. boydi was toxic to Misumena vatia (a spider common in this habitat), while other local predators such as Pholcus phalangioides, Stagmomantis californica, and Chrysoperla carnea were unaffected.