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I've read that holes in grapefruits can be caused by birds or pack rats. However, my tree does not have the extent to be reachable by pack rats, and the holes do not look like bird holes. The tree itself is about 6 foot high and slightly wider in the middle. It looks like somebody drilled a hole with a drill about 3/8 inch or so in diameter. This is happening to every grapefruit around the time that it turns yellow. Another site claimed it could be insect damage, and added "insect damage of this type requires no control." I certainly disagree as without control every grapefruit is going to be ruined!

How can I deal with this problem?

Update: Here is a picture of what they typically look like. I didn't measure the depth of the whole but they seem to be between half an inch and one inch. In one case there was a large brown bruise-like ring and the interior hole had some kind of flying bugs in it. This particular one had no noticable bugs: Typical hole with dark interior and brown lining

I also found this one which has a bit bigger hole but is not as deep: Atypical larger hole without dark interior or lining

To test the theory of whether it is birds or something else I am leaving both pieces of fruit on the ground to see if they are attacked further. Hopefully this will attract whatever it is so it will leave the tree alone.

Update: This weekend I found a large hole in my bird netting, and a ruined grapefruit on the ground outside the net. I came out later in the day and startled a roadrunner near the tree. Given its long beak, size, and tendency to walk along the ground I'm now thinking that it may be the culprit - although it seems strange that it would like grapefruit instead of lizards. I put up a temporary metal fence around the tree using rabbit wire, so we will see if that fixes the problem for good. However it would be nice to find a better solution, short of attracting coyotes which in turn would be trying to eat the kids. ;'-(

  • 9.5 mm? That's a big hole! How deep? Pix? – Wayfaring Stranger Oct 29 '17 at 14:30
  • Michael, as @Wayfaring Stranger said, we could really use some pictures. Would you show us the whole tree, and a good close-up of a damaged grapefruit. A picture of a grapefruit without damage would be helpful too. Thanks! – Sue Saddest Farewell TGO GL Oct 29 '17 at 15:41
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Leaving sacrificial fruit on the ground did nothing.

What solved the problem for me was buying some bird/rodent netting and covering the entire tree with it. I used some rocks at the bottom to hold the netting to the ground to not allow anything to go under the netting. As soon as the netting was up, no more holes appeared in the fruit!

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I wonder if this is stink bug damage but they aren't supposed to attack grapefruit due to the thick rind. The insects are very large, and I note that you have seen some flying insects in the holes. The solution is to get the fruit off the tree before it all gets damaged.

https://www.orkin.com/other/stink-bugs/stink-bugs-and-citrus/

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  • The insects in the trees were very small, almost gnatlike. I did find an apparent solution though - thanks for reminding me, I should post an answer regarding what I found. – Michael Feb 15 '18 at 16:46
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These holes are caused by fruit flys. I have lost about 20 grapefruit from my tree. The female strikes the grapefruit and lays eggs in the skin. The larvae eat a hole in the fruit from the inside and grow into more flys. I made homemade fruit fly traps from jars, apple cider vinegar and wax paper with holes tied over the top. Put them at the base of the tree. In about 15 minuites, I had thousands of flys in the jars. I have ordered yellow sticky traps to hang in the tree. Also clean up any fruit with holes, seal in a plastic bag, leave in the sun and dispose in the trash. Don't leave fruit with holes laying around. Just breeds more flys.

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mary lou is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
  • how deep inside do the larvae start eating? i caught one the other day with a hole that appeared to not quite reach the inner skin. It didn't appear to have any infestation so I brought it inside and washed it and ate it a couple days later carefully avoiding around where the hole had nearly penetrated the skin. A couple other I was too late and they did appear to have fruit flies of some sort buzzing about. I'll definitely try what you said. – Michael Nov 21 at 20:54

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