Besides black flies, Windswept Farm is plagued with Colorado Potato Beetles (CPB – Leptinotarsa decemlineata), whose larvae will chew a potato plant like a dog chews a smoked pigs ear, and almost that fast. They don’t touch the tubers underground, but if there’s no plant to feed the tubers, you don’t dig potatoes in October. They are a scourge not just here in Monroe Maine, but around the world despite originating in Colorado. The Wikipedia article mentions that they may have been used as a crude form of biological warfare against Germany in WWII, and the Soviet Union in the 1950s.
What makes them so insidious is their high tolerance to many pesticides, as well as their ability to develop resistance to specific pesticides very quickly, probably because of their short lifecycle and high number of offspring (thousands per female).
One pesticide that has been very effective against CPB is called “Bt” which are the initials of a soil bacteria that produces a substance that causes CPB and only CPB larvae to stop eating, and thus die in a day or two. Because it’s targeted to CPB (i.e. doesn’t kill ALL insects it touches like many pesticides), and it’s derived from a “natural” source, Bt has been approved for use in organic production. However, because it’s so effective against CPB, the bacterial genes that produce the effective substance were one of the first that were genetically engineered to become part of the GE versions of potatoes, most famously called “New Leaf” variety/brand. The difference there is that when you spray Bt on a leaf, where it is eaten by the larvae, the Bt eventually washes off the leaf and/or degrades in the environment, never to touch the edible part of the crop. When it’s engineered to appear in every cell of the plant, we then eat Bt with every french fry.
Anyway, if I can’t pick the bugs and larvae off the plants fast enough (which is often) I will use Bt spray on my potatoes, as well as rotenone (another organic pesticide that is not targeted to CPB, so I use sparingly) when they get too old to be affected by the Bt. Today is Sunday, which is when I do my once-a-week weeding of my garden, and I also brought a plastic cup down with me to pick CPB (which I have to do almost daily, actually). Pictured is my harvest. It is interesting to note that the CPB seem to prefer certain varieties of potato over others — I picked more than half of these beetles off of the Green Mountain potato plants. (Green Mountain is an heirloom Vermont variety that makes good dry baking type potatoes without a thick russet skin.)