Posted Wednesday, May 14 --- 5:00pm

It's a bite that causes welts, swelling and continuous bleeding and the culprit is the little black fly.

The little black fly is usually found farther north, toward the boundary waters, but entomologists say from time to time they make their way into Southern Wisconsin.

However this year, the little black flies are more widespread in what one entomologist is calling an "intense phenomenon."

McKayla and Sarah love to play in the backyard and especially love to swing. But now, they're a little more nervous about playing outside after they were bitten by a then unknown bug. McKayla's mother Megan Fox says, "I noticed them all over Kalen and he had all of the sudden I got him off he started bleeding like immediately, so then we grabbed McKayla and looked at her and that's when we noticed she had a lot of blood on the back of her head." Instantly alarming both moms. Renee Noltemeyer says, "I really started getting concerned because I didn't know any bug that did that."

After some of the bleeding wouldn't stop, and the welts continued to swell, they took the girls to Urgent Care. Noltemeyer says, "He said it was just a little black fly and I'm like well, it doesn't look like a house fly at all."

The little black fly is compared to a buffalo or turkey gnat. Entomologists liken them to fruit flies on steroids which migrate to Southern Wisconsin from time to time, but are not usually this widespread.

Dr. Tim O'Neil with Dean Health Urgent Care says, "The bite is not serious, I don't think they carry any significant illness with them." However, symptoms are generally mild and treatable ranging from intense itching to a low fever or feeling lethargic. Doctor's say children and adults are susceptible to the bites, which are most commonly found around the hairline and on the scalp. Dr. O'Neil says, "These little black flies are sneaky, they like to land on the collar so you can't feel them and bite over the collar."

Doctor O'Neil recommends if you're going to be outside, do as McKayla and Sarah now do, wear a hat and kid friendly bug repellent.

Entomologist Phillip Pellitteri says the bites should only last four to five days and should only be widespread for about the next two weeks.