Japanese Beetles

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Japanese Beetles

Have been in the United States for over 100 years. They have slowly made their way from the east coast to the Mid-West. Strict regulations on shipping live plant materials from affected to unaffected states has helped control the infestation, however, it was inevitable that they would someday reach our area. The beetles have been in Austin for about 7 years, they now seem to be widespread throughout the town. Preventative treatment for Japanese Beetles is crucial because they have no natural predators. Japanese Beetles have a 6-week mature life cycle. The rest of their life is spent in an immature stage as grubs (which look like white worms). At the mature stage, the beetles eat, mate and lay eggs. Each female beetle lays 50-60 eggs in the ground. These eggs hatch as grubs. The beetle grubs live in the soil, feeding off of roots, generally from grass. Because they spend 10 ½ months in this grub stage it is crucial to treat lawns with grub control. If turf areas are not treated: 1) the beetle infestation multiplies rapidly; 2) dead brown spots begin to appear in areas where the grubs have consumed almost all the roots of the turf, killing the grass; 3) it is likely moles and voles will infest the area because the grubs are a food source for them.

Treatment Steps:

Grub Control

1. Apply grub killer April-May or August – October
a. Grub Killer Options (Choose ONE Option)
i. Annual grub killer application. This application is done in the same method as a if fertilizing the area with a granular fertilizer. The grub killer is applied through a push lawn spreader.
ii. Milky Spore. Milky spore is a live bacteria that lives in the soil. Once applied correctly the application lasts for 10 years.

Adult Beetle Control

2. Japanese Beetle traps
a. Japanese Beetle trap attract the beetles with a pheromone lure. The traps are most effective if they are hung in early June (before the mature beetles are seen). The beetles are attracted to the lure, fly into the bag and cannot fly out. The lure cover an area no bigger and 1/8th of an acre (beetles will not come from the neighborhood to the trap). Most homeowners do not realize how many beetles they have until the traps are hung. CAUTION: DO NOT TRY TO EMPTY BAG TO CONSERVE, REPLACE BAG.

3. Insecticide Sprays
a. If beetles seem to be particularly bothersome on certain plants, spraying them with an insecticide may be necessary. The insecticide work very rapidly to kill the beetle, but you have to spray the beetle for it to be effective (the spray has no residual effect).

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