Hello readers,
In this series I'm going to break down the basics of garden pests, what to look for, what climate attracts them and methods of getting rid of them. Today's topic: Japanese Beetles. Likely transported in soil to western nurseries this invasive species is notorious for eating everything and anything in its path during summer's high time.
Japanese Beetles:
When do they emerge?
August to June - 11 months larvae, aka grubs grow in the soil
Once temps are above 60 degrees, consistently beetles will be out
Adults emerge in June and feed during the hottest parts of the days and on sunny days, tuck back into soil at night
Predators?
Birds and praying mantis
Both are relatively ineffective, but will eat them
Birds, moles, skunks etc prefer pupae to adult beetles
Best methods of getting rid of them?
Picking them off and throwing in bucket of soapy water
Won’t drown right away, but soap prevents them from flying
This practice should only take maybe an hour a day
Beetles go from high to low, starting with the buds
Prefer fragrant light colored roses
Shaking blooms over the bucket of soapy water is a good method as well.
Best to do daily removal, than every few days because they like to feed in groups
Life cycle?
Grubs grow for 10 months underground after feeding on plant roots throughout the winter months.
Adults emerge in mid-June, July and generally won't do too much damage alone, but together in a group of beetles can cause major destruction.
Adults will leave pheromone on leaves to attract others for mating, partying etc
Females lay about 40 to 60 eggs per season and most larvae have no trouble overwintering as they bury themselves deep into the ground to keep warm til summer arrives
The total adult growth-cycle above ground only lasts about 30-45 days, but they do a lot of damage during that time.
How to ID damage?
In turf, grubs will eat the roots of the grass. You can spot it easily if you have a lot of brown patches that are pulling up with little resistance. Like "pulling up a carpet"
Adult beetles feed on tissue between the veins of various vegetation
Gives foliage a skeletal or lace look
Trees look scorched
Rose blooms can be eaten whole. But you'll find holes in the petals and the beetles like to hide within the crevices of the rose bloom, between the petals and not necessarily at the center.
Most vegetation, rose included, will not suffer permanent damage from these critters. However, vegetables are another story and will likely provide a smaller harvest