potato Bug #645119 - Ask Extension

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potato Bug #645119

Asked June 02, 2020, 7:55 PM EDT

I found some of the leaves on my potatoes are shriveled, dead at the end or have holes in them. When I flip them over I find small, brown, triangular shaped bugs, like the attached photos. Would you please identify, and let me know if I should just pick them off and dispose, or if some other option is better. thanks.

Harford County Maryland

Expert Response

This insect is a Keel-Shaped Treehopper (Entylia carinata), and they appear to have eggs (or young) attached to the stem next to the adult in each photo.
https://www.marylandbiodiversity.com/view/6252

https://bugoftheweek.squarespace.com/blog/2017/9/28/deception-and-defense-on-cup-plant-keel-shaped-treehopper-ientylia-carinatai

https://content.ces.ncsu.edu/ientylia-carinatai-the-keeled-treehopper

They can be tended (like cattle) by ants, who feed on their sugary secretions. (There's an ant rear end visible in the last photo.) The treehopper's feeding on the plant sap may be what is causing the shriveling and dying of the potato leaf tips. Although they seem to prefer Aster-family plants, they have been reported on Nightshade-family plants (potato is a member) as well. They do not transmit plant diseases.

Physically removing them may be the simplest approach, since mothers guard their young (other leaf and treehoppers tend to jump away when disturbed). You can pick them off by hand or clip off the portion of the leaf (or the entire leaf) where they are found, if not too numerous.

Holes in the potato leaves are caused by another pest, though we cannot see any signs of them in the photos. If a chewing insect, a spray of an insecticide containing spinosad may work with minimal impact on beneficial insects. Check the product label to verify its use on potato plants, plus instructions for use and re-application timing. If the hole damage stays minor and doesn't measurably increase, you may not need to do anything to treat it.
https://extension.umd.edu/hgic/topics/potatoes

Miri
Thank you for the information. You said there are eggs that the female is guarding in my photos. So I should probably dispose of the whole leave to get rid of the eggs? I wouldn't want them to hatch in the future. 
Also, now that I have these bugs in my garden, does this mean I will see Them every summer? Is there a way to prevent future infestations? ie skip a year of planting potatoes, plant a different variety?
thank you
 Terry
The Question Asker Replied June 03, 2020, 8:11 PM EDT
She is guarding eggs or already-hatched young, yes - juveniles are not likely to have wandered out of the cluster since it affords them protection, so removing the entire leaf or just that end section should be fine.

Seeing them every summer is not guaranteed, as the can feed on other plants and predators may yet reduce the rest of the local population. Their alternate food sources also means that skipping a potato crop won't have a measurable impact on their presence, as it might with other more crop-specific pests. You can monitor for them starting around late April or May next year and consider using a low-impact pesticide then, if they cannot be physically removed. Alternately, you can try covering the potatoes with a very fine gauze-like fabric such as light-colored mosquito or no-see-um screening. This will allow most of the light to still reach the crop while physically blocking insects this size from reaching the plants. Floating row cover fabric would also work, but might block a bit more light than desired.

Miri

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