Hold on to your lunch. Maggots have been approved for use in wound care in the US since 2004, but new studies are raising questions about whether or not they actually help the wounds heal or just do quick work while seeming kind of gross.

Wounds that don’t heal easily have to be treated to help make them heal. Doctors usually do this by scraping them with a scalpel or applying enzymes to remove dead tissue. This process of debridement can also be done by maggots. The sterile maggots secrete substances into wounds that liquify the dead tissue and then they ingest the tissue and break it down as they digest it.

Some researchers believe the maggots might offer antibacterial and healing benefits in addition to keeping the wound clean. One French study compared patients during a two-week hospital stay. Participants were blindfolded and either treated with a scalpel or with a bag of maggots placed on the wound.

They reported that patients in the two groups felt no difference in pain or crawling sensations. And, after one week, about two-thirds of the wound area in patients treated surgically was covered with dead tissue, but only about half of the wound area of those treated with maggots was covered in dead tissue.

The dead tissue is what interferes with healing, so the results showed that the maggots seem to assist in the acceleration of cleaning wounds. However, after two weeks, the benefits vanished and there was no difference in wound closure. Meaning that overall, the maggots clear out the wounds faster, but do not help healing any more than a scalpel does.

Based on previous studies, researchers theorize that maggots might be useful in preparing wounds for grafting, but that has not yet been proven.