Category Archives: Obsession


Japanese Beetle

Insects are part of life.  I mostly ignore them unless they are deer flies or horseflies.  I get swollen welts the size of a cupcake when they sneak up and get me.  Denver is pretty dry, so mosquitos aren’t much of a problem.  Bees and wasps won’t bother you if you don’t bother them.  Flies in the house are a nuisance but they are easy to control.   

Insects in the garden can be a problem, but they can be controlled as well.  There is one huge exception, however.  Japanese beetles are evil, vile, nasty creatures masterminded by Darth Vader, the Empire, and the Borg.  They eat, kill, and destroy.   

Four years ago Denver had no Japanese beetles.  Then, someone in one of the upscale neighborhoods brought in some plantings with beetle larvae in the soil.  They are rapidly spreading northward.  Two years we had a few, last year they were a plague.   


What do they do?  The beetles themselves eat leaves.  They love rose blossoms, but leave those leaves alone.  They like linden tree leaves, grape leaves, raspberry leaves, and peach tree leaves.  A rosebud opens in the morning and by noon the flower is gone.  They work on grape leaves to the extent that any new growth stops.  That is no good when you are trying to grow a grape arbor.  Lots of linden leaves get honeycombed, but the tree seems to be able to cope.  Our peach tree and the raspberries get attacked, but so far, not a lot of damage.   

In Palisade, over on the Western Slope, peaches and vineyards are the mainstay of the economy.  Unchecked, the beetles would have wiped them out, so they took the nuclear option.  They sprayed.  Spraying stopped the beetles, but it killed the beneficial insects as well.   

Japanese Beetle Grubs in a Lawn

The other part of the Japanese beetle life cycle is when the beetles fly down and lay their eggs in the lawn.  The eggs hatch, and the grubs start eating the grass roots.   Lots of eggs, lots of grubs.  They can be so dense as to form a living mat of grubs.  The lawn develops spreading dead spots.  Uncontrolled, no lawn. 

What to do?  In the morning go out and flick the beetles into soapy water.  Nematodes and milky  spore help with the grubs.  There is a grub poison called GrubEx, but it isn’t selective in what it poisons.   


A popular control is traps.  The kind where the beetles fly into the jug, attracted by some bait.  They drown, and give off a scent that attracts more beetles.  Soon, it is a beetle feeding frenzy with beetles coming from the entire neighborhood.  They look around for another snack and eat all your plants.  You can’t have the trap near your vulnerable plants, not easy on a small urban lot.  I think I will do it anyway, just to watch the evil creatures die. 

I don’t think we will have a grape arbor.  The linden, peach tree, and the raspberries will cope.  We will cut off all the rose buds in June and July.  We may have to eliminate what lawn we have left after years of reducing its size.  

My task is to give up on my beetle obsession.

 Japanese Beetle