Locust Borer – Pretty and Pretty Bad


Yesterday I was on a trip with the bird watchers from the Buffalo Ornithological Society. It was difficult to get photos of birds, as many were REALLY far away. The birders ALWAYS spot numerous birds, but birds are quick and rarely close enough for the camera.

I saw dozens of migrating Monarchs though, making my day. The pretty Monarchs will be coming up along with other critters I encountered. Many in the group discussed the declining Monarchs, wondering about what we might see next year. Everyone with a camera was snapping their photo.

I hope you did not miss Black Saddlebags Dragonfly – Pretty and Pretty Good. It looked at a dragonfly that was plentiful at this time of year in our area. Plus it is a good insect…

Today’s post is on an insect – a pest insect. A pretty pest, but still a pest to a tree. Which tree?


Locust Borer

The Black Locust, which grows natively from the Allegheny Mountains through Pennsylvania to Georgia into Arkansas and Oklahoma, expanded its range a while back due to widespread use to reforest damaged land.

Used as a shade tree in reforestation, the borer you see in this post populated right along with its host tree over much of the United States. Black Locust, Pink Idaho, Robe Globe and Frisia (Want info on Frisia?) are popular large shade trees. Being a fast grower helps explain the trees use in reforestation, plus bees like it. Frisia, a very big seller here at my friend’s nursery, is profiled on Gardening Gone Wild coincidentally the same day as this post, so I added their link.

The Honeylocust trees, Shademaster, Skyline, and Sunburst are not affected by this borer. These are also very popular at the nursery – huge sellers.

Adult Locust Borers are most noticeable in September when the Goldenrod comes into bloom like you see in this post. Meadows are blooming with Goldenrod now, so the Locust Borer was easy to find.


Borer larvae tunnel into a tree’s trunk and branches, weakening and making it susceptible to wind breakage. Seeing the adults in numbers is a sign they have invaded trees with their young. Not only are the borers a pest, but the tree itself is an alien here in NY and gets culled in areas being returned to native plantings.


Megacyllene robiniae

Robinia pseudoacaia is found in the Niagara Park system, but in small numbers.


These insects are easy to spot in a meadow filled with Goldenrod. They are colorful and striped similar to yellow jacket wasps. Often people confuse them with the wasp when seeing them in numbers on the Black Locust.


Seeing the insects enlarged shows the differences. The long, slender antennae and red legs of the Locust Borer really set it apart from the wasp. The Hickory Borer looks like this insect, but appears in Spring, not Fall. They feed on dead wood.


Trees weakened or damaged can be killed by a large infestation of the larvae. Drought stress weakens trees, making them highly susceptible to attack.


I grow Goldenrod, seen above, but no Locust Borers.

About Garden Walk Garden Talk

I love to photograph, paint, draw, design, garden, travel the world, and pass on a few tips and ideas that I learned through experience as a Master Gardener and architect. I am highly trained in my field and enjoy my work each and every day. I garden in Niagara Falls, NY in zone 6-B. Find me at:
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20 Responses to Locust Borer – Pretty and Pretty Bad

  1. barbie says:

    Oh dear! He looks like he can be a big problem! I had the fig borer and nearly lost me fig tree! The chickens and I scratched out the larvae! So far so good!

  2. Gorgeous photos, such a shame his a pest, its a stunning beetle, the colors are amazing!

  3. Great shots, Donna. I’m in agreement with you, it is a ‘pretty’ insect but not at all a welcome one! I’m glad you aren’t growing them in your garden! thanks for the info…

  4. connie661 says:

    It is an attractive looking creature, even if we find it harmful.

  5. Alistair says:

    Perhaps he wasn’t at the front of the queue when it came to looks but he does take a good picture with your guidance. Don’t give him my address though.

  6. Pat says:

    Beautiful photos of a bad character.

  7. Oh my, what a nasty beastie! But your photos were great and the goldenrod is awesome. Have a great day. Blessings, Natalie

  8. bittster says:

    My plan this winter is to get through your photography tips and links page. These photos are great!

  9. Fergiemoto says:

    Very pretty bug…too bad it’s a bad bug, though.

  10. Kevin says:

    Absolutely fascinating. I have never heard of this insect — and I hope I never see one.

  11. I’m glad to hear it’s not a problem for Honey Locusts–we have three in the front yard. I’m glad you saw so many monarchs! Your Goldenrod is beautiful!

  12. How lovely that you saw the monarchs, Donna! I also grow goldenrod, but have no Locus Borer, I’m glad to say. P. x

  13. I will be on the lookout for this beetle. My goldenrod is blooming now too. Does it have a predator? Love the shot of the goldenrod and aster.

  14. Locust is one tree that I don’t have in my garden although they are all around here. I love the flowers and thought of planting one.

  15. Nordlaedchen says:

    These are beautiful photos. Your report is very informative, I had only taken the insect in the photos. Greetings from Germany, dear Uwe

  16. catmint says:

    I wonder if the insect is a problem pest to the tree in its original indigenous habitat? Also the yellow theme is interesting, I guess it evolved that colour for camouflage in the host tree. The Golden Rod must be part of the system, but it’s not clear exactly how.

  17. To Catmint and Karin,
    The Goldenrod is a feeding plant for the adults, but is also to make them less noticeable to predators. The marking are to mimic the yellow jacket which will keep it safer from predation. It feeds on pollen of the Goldenrod. Birds are surmised to feed on them, and the woodpecker was observed by researchers doing so. But mostly, the birds take the larvea and instars.

    To everyone that commented, thank you. I will get back to commenting soon.

  18. Bill S says:

    Stunning photos as always Donna, I would be grateful however if you would keep him in your part of the world !

  19. A.M.B. says:

    The Locust Borer looks so beautiful in the golden rod! Great pictures, as always! I learn so much from your posts.

  20. You make the goldenrod look luscious….borer is colorful.

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