Tuesday, April 23, 2013
Oh No You Don't!
I have recently discovered a pest that only eats asparagus, and it is in my garden! It has a rather benign name, the Common Asparagus Beetle (Crioceris asparagi). These little buggers can breed two to three times in a season and the adults will overwinter in the asparagus patch. The adults and the larvae will both eat the plant. I didn't go Chuck Norris on them when I first discovered them, because I had not identified them. They could have been a beneficial insect for all I knew. Boy was I wrong.
Now that I have positively identified them, the gloves are coming off, this is war. I didn't plant my asparagus patch and wait three years to eat it, to have these mono-diet Coleoptera monsters eat it all. They look cool though, sorta like a badass ladybug.
These beetles will eat every part of the asparagus plant above ground. You can see bite marks all over this stalk. If you look closely at the bottom of this picture, you will see an asparagus leaf with a hole in it. These are some of the smartest beetles I have come across. They seem to sense my presence and play, ring around the asparagus stalk, whenever I get close.
You can see the eggs of the beetle all over this stalk. The eggs hatch in three to eight days.The grubs will then feed on the tips of the stalks. As soon as the grubs are mature they drop to the ground and pupate in an earthen cell. The adult will emerge from this cell and start the whole process over again. This cycle can happen two to three times a season. Thankfully, there is a natural predator for the common asparagus beetle. It is a small parasitic wasp called Tetrastichus asparagi. This tiny wasp will lay about six of its own eggs in each asparagus beetle egg it finds. I hope to see some this year.
The eggs are often laid in rows of two to eight. They are easy to kill at this point. They almost pop when you touch them. In a small home asparagus patch like mine, you can manually manage the infestation by visiting your patch and removing beetles and eggs everyday until they are gone. You will have to keep an eye on your patch later in the season to make sure no other beetles fly in and re-infest. You want to cut the leftover stalks to the ground so the beetles have less to lay their eggs on. I have read some people burn their dried out asparagus patches in the winter or early spring to kill the overwintering adults. Seems like that might hurt your crowns, but it appears to work from the multiple sources I have read.
One way to manage them is knocking the beetles into a glass of soapy water. I found they almost sense what you are about to do and drop to the ground when you get close to them. After losing about five this way, I decided to just grab them in my fingers and dispatch them. Squishing them is much more satisfying than soapy water, but both methods work. Large scale operations use pesticides to manage the problem, but if you have a home patch or two, manually removing them should work.
This is what it is all about. Fresh, healthy and free vegetables growing with minimal input, year after year. We had asparagus wrapped in bacon last night for dinner. It was worth every minute I spent planting, weeding and protecting my asparagus patch.