By Bev Johnson

Master Gardener

In June, the University of Minnesota had a research team that was willing to come to your house and dig up some grubs. 200 gardeners offered their yards, more than the U had teams for. The problem with grubs isn’t just that they destroy our lawns, but the June beetles they grow up to be, eat grapes and elderberries and distort the fruit so it rots. This reduces food for wildlife and people. The racoons and crows that tear up the lawn looking for grubs just magnify the problem. This stinker isn’t even native. It showed up in 1917, probably imported in the soil around a plant from overseas.

Vera Krischik, an Entomologist, is one of the leaders doing research on the grub problem. She is looking for an organic product for at least, reducing the number of invasive grubs that started to show up in the late 1960s.  So many of the insecticides the homeowner has available are deadly to butterflies and bees. The only exception is Scotts GrubEx. Several years ago, a bacteria that had been working in some of the organic offerings, was removed by the federal government. Who knows why.

A pathogen called Ovavesicula, common in some of the Eastern states, is getting a good look. The question is why their soil has more of the spores of this pathogen than ours do. If that question can be answered by professor Krischkik, she may be able to predict where to release this pathogen to make it go faster. Researchers at Michigan State determined that it took about 6 years for the pathogen to spread like a sickness to reduce the population of grubs by 90 percent. Then how to get the stuff to the grubs. Do they spread it directly on the soil, or by traps. Or, can we infect compost and kill grubs spreading infected compost on our grass?

One way to deter grubs is to let the grass go dormant, brown and dry.  Grubs want a nice, blue-green lush, well-watered lawn. Do that and the neighbors will haul you away and probably tar and feather you. Well, at least call you nasty names.  

Another way may be a worm that liquefies grubs and sucks up the fluid. The hammerhead worm, a striped flat worm that looks like a 2-foot hunk of whole wheat spaghetti, with a mushroom shaped head. It most likely came in soil from exotic plants imported from Asia. It is already in Milwaukee so they may be on their way here. This is not a good thing as this worm secretes a debilitating neurotoxin found in puffer fish. Eat a pufferfish that has not been properly prepared and you’re dead. However, you would have to eat a gob of worms to get that effect and most people draw the line at eating worms. Some of your pets may not have the same problem. Handling them can cause skin irritation.  The worm doesn’t like light, so you won’t see them during the day. 

While killing grubs is to be encouraged, they also kill earthworms. It’s a gruesome thing to watch. They crawl on the worm and rub their head on it, probably releasing their toxin on it. The earthworm stops moving. The hammerhead worm then secretes digestive enzymes that liquefies the earthworm’s tissues. He then sucks the earthworm dry. ICK. They have the potential to damage other invertebrates that can cause risks up the food chain, definitely not a good thing.