Sticky stuff dropping from my trees - bug droppings? - Ask Extension
Our patio furniture is covered with sticky stuff that I fear is not sap. Once a few years ago, a tree company told us we had mites or something and th...
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Sticky stuff dropping from my trees - bug droppings? #831833
Asked May 24, 2023, 1:10 PM EDT
Our patio furniture is covered with sticky stuff that I fear is not sap. Once a few years ago, a tree company told us we had mites or something and this was what was dropping on us on that patio. I got the impression the black stuff on the bark (and on the wood of our pergola) was from bug poop, but I may have that wrong. The other problem is, I have free range hens. Any poison I use on the tree might be dangerous for them. I don't know how to address this situation! Would appreciate any advice. Thank you.
Denver County Colorado
Expert Response
It looks like you have a mature Ash tree. Ash can be colonized by aphids, scale and other insects which produce "honeydew," a polite term for the sticky substance the insects excrete. It can be a serious nuisance on patios and cars and it supports the growth of a fungi called sooty mold - which is what the photo of the tree crotch shows.
Some of your options include spraying the tree with dormant oil over the winter to kill the overwintering eggs or you could use a systemic insecticide during the growing season to kill the adults. If you coop the chickens while the tree is being sprayed, the controls should not hurt them. Alternatively, you may opt to do nothing. There are natural controls like parasitic wasps and birds which will help control the insects. You'll have to put up with the nuisance of the sticky honeydew but the outbreak should subside by mid-summer.
Here is an article you will find helpful. It discusses aphids on shade trees specifically and we don't know for sure that's what insect is in your Ash as the honeydew also might be from scale, but either way, the general information applies:
https://extension.colostate.edu/docs/pubs/insect/05511.pdf
Some of your options include spraying the tree with dormant oil over the winter to kill the overwintering eggs or you could use a systemic insecticide during the growing season to kill the adults. If you coop the chickens while the tree is being sprayed, the controls should not hurt them. Alternatively, you may opt to do nothing. There are natural controls like parasitic wasps and birds which will help control the insects. You'll have to put up with the nuisance of the sticky honeydew but the outbreak should subside by mid-summer.
Here is an article you will find helpful. It discusses aphids on shade trees specifically and we don't know for sure that's what insect is in your Ash as the honeydew also might be from scale, but either way, the general information applies:
https://extension.colostate.edu/docs/pubs/insect/05511.pdf
