What's Digging Up My Lawn??!!
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Q: Jens in Burien ("BEWR—eeen"), Washington (which is South of Seattle on the Puget Sound) writes: "I'm sure you've answered this question on a blog or podcast, but I couldn't find it. I woke up one morning to find my front lawn in tatters. A local master gardener thinks we have an infestation of chafer beetles, and that birds and/or raccoons are digging up the lawn to get the grubs. A local lawn care company wants to spray Sevin on the lawn. I was hoping to get a different recommendation from you. The damage is very bad."
A. First, the best way to find information on a topic we may have already covered is to go to the searchable archives of over 500 of our previous questions of the week at the Gardens Alive website—which you can easily access via our website, "You Bet Your Garden dot org."
Second: "Sevin?!" What is this—the 19th Century? Sevin is an old-school chemical pesticide that is incredibly toxic to bees and other pollinators—especially in its 'dust' form, which is exactly the type used on lawns to control the grubs of destructive scarab beetles like the rose chafer. Non-toxic and highly effective alternatives abound; the newest of which is BTG—a newly-developed strain of the naturally occurring soil organism Bacillus Thuringiensis.
Just be sure you get the right kind of "Bt". The first strain developed, BTK, kills pest caterpillars (but not bees, butterflies or anything other than caterpillars). BTI is added to standing water to prevent mosquito eggs from hatching into biting adults (but that water is safe for bees, butterflies, frogs, toads and pets; BTI only works against biting insects that breed in water). The new kid on the block, BTG, works against both adult beetles and their underground grubs.
Gardens Alive—a financial supporter of our radio show but also instrumental in the development of this non-toxic insecticide—offers the grub killing form via mail order as "grubHALT". (The product may be available at retail under other brand names, but I couldn't find any.) You water BTG into a grub-infested lawn and it will quickly kill any grubs who get a bite of it while feeding on the roots of the lawn. It will not harm any other type of soil life; just grubs.
Beneficial nematodes are also highly effective against grubs. Sold by the millions in a sponge-like carrier, you open the little container, drop the contents into a watering can, water it into the soil and the microscopic predators will 'worm' their way into grubs, killing them in the process. Look for newer strains bred specifically for grub control; they're much more mobile and aggressive than basic old-school beneficial nematodes. Like BTG, beneficial nematodes don't harm any other form of soil life…
…which means that you'll be rid of grubs, but not necessarily what's tearing up your lawn, as they may also be digging for tasty earthworms and cicada larvae.
Now: What's doing the digging?
• My number one choice is skunks. Skunks love to chow down on earthworms and grubs and are known for doing a job on lawns. Luckily, skunk damage is generally temporary, explains "Mr. Skunk", Dr. Jerry Dragoo, a research professor in the Biology Department at the University of New Mexico who has studied the oft-misunderstood creatures intensively. As he explains in a previous Question of the Week archived at the Gardens Alive website, skunks generally only feed in lawns as they're passing though an area. But he adds that this can also be a bad time of year to have this happen, as those skunks are also looking for permanent homes for the winter right now and love to live (and stink) in crawlspaces and other areas under homes and sheds. Read the article.
• Or it could be raccoons. These cute little bags of rabies feed on everything—including grubs and earthworms. Beware if you have attracted these creatures; their powerful claws can tear household pets apart; and their feces contains diseases and parasites that can be deadly to pets and humans. AND each raccoon tends to live inside a very small range, so hire a professional removal service ASAP if footprints and scat reveal that's what you got, because you got to get rid of it fast.
o Side note: Both skunks and raccoons are attracted by easy food, like trash in plastic bags and dishes of pet food left outside. Keep your trash in sealed containers with locking lids and don't leave any food outside.
• Although most people despise starlings, they use their long beaks to dig into lawns in search of grubs. Keep an eye out for pecking birds.
• Moles are the most notorious destructors of lawns in search of grubs and earthworms. If there are raised tunnels in your lawn, you got moles. Read some of the detailed articles we have done on these little pests.
• And finally, Evil Squirrels love to tear up lawns to hide food for the winter. If you've had a big nut drop in the wild—or are missing a bed of tulip bulbs—the lawn may have been ravaged by these Long-Tailed Servants of Satan. Read the articles on them; and good luck.
Maybe these clues alone have identified your poop-etrators. If not—and the damage continues, install a motion actived night camera to make a positive ID. Then read the long-form article at our website for your complete options.