They're baaack!! Japanese Beetles are buzzing and flying again and have already begun to feed on some of their most favorite plants including lindens, grapes and roses. With the emergence of Japanese Beetles, people usually also begin to ask about grub control.
First off, in regards to Japanese Beetles – avoid using traps. Unless you really enjoy Japanese Beetles including the ones from surrounding properties, then it's best to not put a trap in your yard. Traps use pheromones to attack males and a floral scent to attract females, and beetles are attracted to the area but don't usually don't succumb to being caught in the trap, so you end up with a higher population of beetles and more damage. I don't know anyone who really wants to have a Japanese Beetle party in their yard.
As for grub control – let me start off saying that even if you implement a grub control program in your own yard (and only if needed) – you will still have Japanese Beetles fly their way into your yard next year. Japanese Beetles are able to fly 10-15 miles. If you have had problems with grubs in your lawn, then implementing control program for a few years to increase turf quality and density can be beneficial. Grubs feed on the roots of turf and begin to cause damage when there is 10-12 of them per square foot. If you have not had trouble with grubs and there is no evidence of grub issues, it not often not necessary to utilize chemical grub control unless you are noticing a high level of adult beetle activity in the area.
One cultural method of helping to reduce the chance or minimize the number of grubs is to let your turf go dormant in the summer in late June to mid-July to minimize potential egg laying in your yard. Adults are more attracted to well irrigated turf areas. Trees can also play a role in helping to minimize grubs as few eggs are laid under the canopies of trees.
Finally, if you do need to apply grub control, apply at rates according to the label on the product in mid-July and then water in well with a ½ inch of water. Products commonly used for grub control work well on young, newly hatched grubs but not well on older more mature grubs, so if you do need to apply chemical controls for grub control, make sure to mark it on your calendar. It's also only necessary to do one application of grub control a year – don't apply grub control in the spring as the grubs only feed for a short period of time making control at that time ineffective.
For more information or questions about turf management or grub control you can contact your local Extension office for more information.