The ‘violet Oil Beetle’ secretes toxins as a defense mechanism. Contact with adults may result in skin blistering due to these toxins, known as cantharidins. Handling or crushing ‘violet Oil Beetle’ can lead to skin contact, causing mild to severe blistering upon touch. Ingestion, particularly dangerous for pets or children, can lead to severe internal complications. Long-term effects depend on exposure level; however, typical symptoms include skin irritation and potential damage to the digestive tract.
From the above link:
That doesn’t sound too bad. I’ve been around cats with a greater potential for damage to the handler.