What’s up with JB?

Tue. Oct. 10, 2017

Click below to listen to my 2 min. Garden Bite radio show:  What’s up with JB?

The last of the Japanese Beetles have gone to warmer pastures and we’re left with the devastation of many of our roses, hibiscus, virginia creeper vines…. And that’s must in MY landscape!

On roses

I just recently read an article from a U of MN entomologist, Jeff Hahn.  He said 2017 was a year of above average numbers of JB.  Although it might appear that JB occur in cycles (like forest tent caterpillars), in fact their numbers are driven by weather. The most important factor influencing their abundance is a lack of soil moisture.

JB eggs and newly emerged grubs are very susceptible to dry soils so during years when we experience drought we typically see relatively fewer Japanese beetles. This was true about three to five years ago when we had some very dry summers.  Since then, we’ve started receiving more normal rainfall and JB numbers have become numerous. Hahn says, that while their feeding definitely affects the appearance of plants, as long as (deciduous) trees and shrubs are healthy and mature, they can tolerate severe, even complete, defoliation.

If trees and shrubs are severely damaged for several consecutive years, they can sustain more lasting injury.  Check out the normal care for trees and shrubs .

Overall, look for most plants to rebound and be fine next spring.  Here’s more information on the Japanese beetle, it’s life cycle and… should you choose, how to deal with the grubs with chemicals.

We do NOT recommend JB traps – the information now coming out indicates it only attracts MORE…

The question now is… what about next year?  Well, with the rains, we will likely see similar numbers next year… or we’ll have a drought.  Stay tuned.

On my hardy hibiscus
Their death in soapy water