Entomologists from Pennsylvania State University found that deer flies, which sometimes bite humans, are more prevalent in the United States than originally thought.

A recent study revealed that the parasites are now in 10 new states and 122 new counties in North America. Researchers used a collection of data by the public to monitor populations of four deer keds in North America and where they are commonly found. The team also personally collected flies directly from carcasses from deer butcheries in Pennsylvania.

The findings were published in the new issue of the Journal of Medical Entomology.

Deer Flies In North America

The Lipoptena cervi, which was from Europe, was previously only found throughout the Northeast region. However, according to the study, the species of deer fly now occur in Connecticut, Rhode Island, Vermont, and Virginia. The parasites were also found throughout the entire state of Pennsylvania.

The species L. mazamae is increasing its range further into the north and east. The neotropical deer keds were spotted in North Carolina, Tennessee, and Missouri.

Two deer ked species, L. depressa and Neolipoptena ferrisi, meanwhile, were found from British Columbia in Canada, through the United States, and up to Mexico. The species are also already in South Dakota, Nevada, and Idaho.

Danger Of Deer Flies

Deer keds, as the name suggests, often attach themselves on deer fur, but they also can be found on moose and elk. They do not look like typical house flies — deer flies have flatter bodies and deciduous wings.

Like other parasites, pathogens have been detected on deer keds, but the researchers noted that it is still unclear whether they can be transmitted through bites.

"Deer keds can run up your arm while you're field dressing a deer and bite you," warned Michael Skvarla, director of the Insect Identification Lab at Penn State and the first author of the study. "If these insects are picking up pathogens from deer, they could transmit them to hunters ... We don't want to scare people, but people should be aware there is the potential for deer keds to transmit pathogens that can cause disease."

Skvarla and colleagues will continue to study deer ked populations in North America. They are hoping to screen deer keds for pathogens by looking at their salivary glands and guts. Skvarla said that this will determine whether the parasites can transmit pathogens to humans through bites.