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Ground nesting bees and Carpenter bees may look scary, but they're really harmless garden helpers!
Question. Dear Mike: Every year at this time, my front garden is inundated with swarms of fly-like insects that burrow into the earth and make holes. This area is partially covered with ivy and dead leaves, but there are also bulbs, hostas and other things. I just cleaned out all the dead leaves and other material hoping that might help. HELP!
---Isla (pronounced ILA [like 'island']) from Elkins Park, PA
Mike: We have some sort of bee/wasp type insect that comes out in the spring through many holes in the ground (particularly under a pear and cherry tree). Do you know exactly what they are and how to get rid of them? We have a toddler, they have been hanging out on her bright yellow slide, and we want them gone before she gets stung!
---Laura in Philadelphia
Answer. Well, thank you, ladies—it's been a while since I've had the chance to educate our listeners about these wonderful Native bees. Yes, that's what they are—several types of ground nesting Native bees are very active in the Spring, pollinating our early-flowering plants. (Those bees probably think that bright yellow slide is a forsythia bush—at least till they try and find the pollen!)
There's nothing to worry about—unlike yellowjackets (which also nest in the ground, but only in the FALL, never in the Spring) these bees are very gentle. The males can't sting. (That's why male bumblebees—another Native bee—act so menacing sometimes; the best those guys could do is head-butt you.) The females could sting, but being women, know better. (That's probably why the guys DIDN'T get stingers.) You'd have to grab one to get stung. And even then, you'd have to grab a female.
Dr. Terry Griswold, a research entomologist at the USDA's Logan Bee Labat Utah State University (http://www.loganbeelab.usu.edu/) says that a number of Native bees look a lot like flies, including at least one 'gregarious' species that's active very early in the Spring. I think I know these guys! Just last week I had a lot of bees that looked a lot like flies paying a huge amount of attention to the pussy willow I deliberately planted smack dab in the middle of my garden to attract pollinators.
And that's the BIG reason to leave these great bees alone—they are far better pollinators of food plants and flowers than the imported honeybee (a European immigrant; NOT a Native bee). Natives fly earlier in the season, work longer hours and aren't afflicted by the numerous pests and diseases that attack honeybee colonies. And they're better pollinators in general, greatly increasing the number of flowers on your ornamentals and the quality of your food crops—especially those fruit trees!
So do nothing. The bees are really active because they're nest-building right now. They'll soon settle down and virtually disappear—except for when you spy them visiting your plants and improving your garden's floweriferisness. Just wear sandals or flip-flops when you're outdoors during their active times in case you should accidentally step on one.
And if you decide these gentle bees are not welcome next year, put in a nice thick lawn! They only build their little nests in bare ground or turf that's in terrible shape.
Question. Mike: I have battled carpenter bees for years. They've been slowly destroying my deck with multiple holes. Local nurseries and garden shops have no real suggestions; they just point me to a can of Raid. I have sprayed the Raid around the deck once a week, which does seem to help, but I hate using it since I have to spray upwards and it's very easy to inhale some of the fumes, which I suspect is rather dangerous. I wish I could hang something from the deck to ward them off. Any suggestions? Thanks
---John in Wayne, PA
Answer. Well, of course we all have one big suggestion to begin with, "John Wayne".
OK, all together now, YBYG listeners: "STOP USING RAID!" Thank you. Well done.
Alright—now, although they are big and fearsome looking, carpenter bees don't sting people (as with other Native bees, the males can't and the females don't). But they are great pollinators who will double the amount of food and flowers in your gardens. AND they rarely—if ever—cause any real damage to wood.
The bees are just starting to build this year's nests in preparation for mating. If you act quickly, you may be able to 'move' them without killing any wonderful buzzers-to-be. Wait till they're all out looking for flowers on the next warm sunny day, and quickly plug up their holes with steel wool or metal screening stapled overtop. You could also spray or brush some almond oil around the area—Cornell researchers found that it repels carpenter bees. Just don't spray the bees! (You can find almond oil in bulk anywhere massage therapists buy their supplies.) Then drill some 'starter holes'—same size as the bees make—into big unfinished blocks of cedar, pine or other soft wood and hang them in a protected area facing South or East near the deck for the bees to use instead.
Long term, you'll need to paint, varnish or replace (with metal or fiber glass) unfinished softwoods like cedar and redwood on the outside of your home. Yes, I know you used those woods because you thought you wouldn't have to do those things, but they are very attractive to wood-boring bees.
Again, these big buzzing puppies are beneficial in the garden, don't sting, and don't cause structural harm. Honest. Reference books note that homeowners almost always overreact to the non-threat they pose. So take a chill pill and enjoy the extra flowers.
Wanna see a blueberry Bee that looks just like a fly? Go to http://www.loganbeelab.usu.edu/, click on "gallery" and then choose "Osima".
You Bet Your Garden Question of the Week ©2005 Mike McGrath