Where have all the grubs gone?

We had to search high and low for these first instar grubs

We are particularly interested in grubs (European chafer grubs that is) this fall because we are planning a grub bio-insecticide trial and we need a site with first or early second instar grubs. We have come up short at the site that we used over the past two years. This site had very high populations of grubs for three years running and the grubs seem to have just disappeared this year. Ditto on a sod field that was reportedly crawling with grubs in the past couple of years that we visited this week.

So my question, where have they gone? It hasn’t been a particularly dry summer, in fact it has been the opposite. During a dry summer, European chafer grub eggs may fail to hatch. Maybe it was too wet? Grub eggs need just the right amount of moisture to hatch. Too much soil moisture is a bad as too little. Then there was last winter. Some people are pointing to the fact that we had such a cold winter that the grubs must have died. Dr. Michael Brownbridge and I did some spring post-treatment counts on our Fall 2013 grub trial and there were lots of grubs to be found then. Maybe it is simply that the grass is so healthy that it will take an army of grubs to cause any turf damage this fall.

Those of you who do not want grubs in your turf will be happy that you have one less thing to worry about this fall. That being said, if anyone on a golf course finds a small patch of grubs in a rough or has a history of grub damage in the rough (we need a 20m x 20m area of grub infested turf) or if you are a lawn care operator and you have an estate customer with grubs we would love to hear from you. We figure we have a two week window to do this trial based on the size of the grubs at the moment. So………. please help us if you can!

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