Thank you for contacting the UVM Master Gardner Helpline with your question about the insects eating your apples and including the picture that was very helpful.

I am so sorry that the insects have been eating your apples. It is unusual that they eat the apples while still hanging and discouraging to lose your harvest after watching them grow all summer.

What you have are yellowjackets. This article from Iowa State University Extension and Outreach entitled “Yellowjacket and Paper Wasp Pests of Fruit” Iowa State: https://hortnews.extension.iastate.edu/2009/8-26/yellowjackets.html has information about the wasps including the following information about controlling them:

“Discourage wasps and yellowjackets from feeding on ripe fruit by harvesting frequently and thoroughly. Pick as soon as fruit begins to ripen and remove all over–ripe and damaged fruit, beverages, candy, lunches and other items that might be attractive to wasps.

“Several yellowjacket traps are on the market that can be used outside the perimeter of the planting to discourage yellowjackets from feeding on fruit. Place traps before the fruit begins to ripen. Different baits and traps may have to be tried to determine if any traps/baits will work in a particular planting or orchard. Place traps early (July or early August) to improve chances of success. Once the yellowjackets have found the ripened fruit, the traps will be of little benefit.

“Finally, nests can be destroyed by applying an insecticide into the nest during the night. This provides control within a few days for those nests that can be located. Do not plug a nest opening in a house wall until you are sure all activity within the nest has stopped.”

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In addition to information about identifying the insects, this article from Pennsylvania State Extension includes information about first aid in the event of a yellowjacket sting: https://extension.psu.edu/tree-fruit-insect-pests-yellow-jackets-and-hornets.

This article entitled “Nuisance Wasps and Bees” from Colorado State University Extension: https://extension.colostate.edu/docs/pubs/insect/05525.pdf has information about a number of different insects, includes first aid information for honey bee stings. I realize that you are not dealing with them, but I thought this information was worth noting:

“First Aid for Stings Honey bees – but not other bees or wasps – generally leave the stinger embedded in the skin. Remove the stinger as soon as possible since some additional venom may be pumped by the venom sac. Honey bee stings are best removed by scraping (not crushing) the stinger with a finger nail or knife blade.

“Localized swelling and pain are typical reactions to a sting by a wasp or bee. In most people, these symptoms gradually disappear within a few hours. Some swelling, itching and pain are all normal reactions and do not necessarily indicate a systemic reaction to the venom of the sting.

“Treat the sting site with an antiseptic to prevent possible infection. Cool lotions or compresses can help relieve pain and swelling. Various materials applied to the sting site may also reduce pain – crushed aspirin, meat tenderizer and urine are among those that have been suggested. If many stings are received oral antihistamines can sometimes reduce swelling and itching.

“A small percentage of the U.S. population (approximately 1 percent) develops hypersensitivity to either bee or wasp venom following repeated stings. A systemic allergic reaction can involve difficulty in breathing, dizziness, nausea and development of hives. These symptoms may require immediate medical attention from a physician.”

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I hope this information is helpful. If you need more information, please feel free to reach out. I hope you are able to save some of this years crop!