Monsters from Across the Pacific

Ames, Iowa (July 28, 2013)

I am not talking about a certain summer blockbuster movie where alien monsters surface from a portal at the bottom of the Pacific Ocean. The alien monsters I am referring to come from all the way from across the ocean. They didn't arrive through an interdimensional portal, but most likely hitched a ride on a regular boat. Their size is quite diminutive, but their shiny armor is impressive anyway. They are the only thing from Japan that I genuinely hate: Popillia Japonica, or the Japanese Beetle!

The beast is in fact quite small (15 mm max, the photo above is a macro enlargement), but the small size does not make it less of a threat. As the name suggest, it is native to Japan, where it is just another cute bug whose population is controlled by natural predators. Not so in the US, where those predators are absent, making the popillia japonica a terrible pest. Probably introduced with a shipment of irises before 1912 (before routine inspections of imported commodities began), it is gradually taking over the whole continent. Four years ago, when we arrived in Iowa, I remember noticing just a few of them. In the last two years their number has grown so much that my garden is repeatedly invaded by hordes that have completely annihilated my favorite daisy flower-bed, and decimated the remaining ones. The beast acts by skeletonizing the leaves of the victimized plant (you know, artistically eating all the green stuff leaving only the network of dead capillaries). Well, despite the colder than usual weather of this summer, my roses are already starting to be skeletonized. If this was not enough, even in the larva stage they are a menace, as they eat the roots of the grass, leaving large dead patches in the lawn. I really hate them.

As I mentioned before, in the US there isn't much in terms of natural predators capable of dealing with this calamity. Stink bugs and blue wings wasp kill Japanese Beetles, but there isn't enough of them around to stop the invasion, by the hundreds, that reach my garden every day. I don't want to spray pesticide near my tomatoes (or where our dog can play), so chemical warfare is not an option. Biological warfare has some limited effect (the larvae can be killed by fungal spore dispersed in the turf), but to work effectively it would need to be applied to the entire town (otherwise I would just be getting the beetles born in my neighbors lawn). Traps with pheromone baits attract more of them than they can catch. In the end, the most effective way of getting rid of this menace is to pluck the monsters one by one from the victimized plants, smash them in minute fragments and scatter their assorted body parts all around the infested area. Gross, yeah, but it seems to teach them the lesson: don't mess with my garden!

PS: no Japanese beetles were harmed to make the photo above. I actually took pity of the bug, and didn't have the heart to squash it after seeing it straight in its multi-faceted eyes. After taking the photo I just picked it up, and freed across the street.