Megan Knapp

Hatching vampires


The life cycle of vampire maggots

Jordan Ellis / For The Post

Vampire maggots is a chilling name, creating the image of something pale slithering in the darkness. For some, it brings feelings of both apprehension and intrigue.

Vampire maggots do exist –– they are the larval form of the bird blowfly, a fly species that lays its eggs in bird nests. The maggots then feed on the blood of baby birds. Their life cycle and relationships with nesting birds is fascinating to scientists, but in many ways they remain a mystery.

“Really, we know nothing about the biology of these blowflies, and we don’t know when they hatch. We don’t know when the females lay the eggs. We don’t know how the females lay the eggs. We don’t know how the female flies find the nest,” Kelly Williams, a lecturer of biological sciences at Ohio University, said.

Williams is a member of the Avian Parasitic Fly Project , which hopes to change that. The project is run by a group of professors and students, and aided by local volunteers. It’s also part of the Cornell Lab of Ornithology’s project Nestwatch , a nationwide program that monitors the reproductive biology of birds. The aim of the project is to analyze the life cycle of the bird blowfly, as well as the sensory and communication methods it uses to perform various life functions. Those involved hope to understand and control the affects the bird blowfly has on nesting-bird populations.

Bird blowflies are obligate parasites, meaning that to complete their life cycle, they must find a host. Bird blowflies are only parasitic in their larval stage. Bekka Broddie, a visiting assistant professor of biological sciences and project team member, describes them as vampire maggots in their larval stage, when their hosts are infant nesting-birds.

The lifecycle of the maggots is time-sensitive. For the vampire maggot to live, the mother blowfly must lay its eggs in a bird nest at the same time a mother bird lays its eggs. That way, when the maggots hatch, it will be around the same time as the infant birds, and they will have a host to attach to.

When it begins feeding off the infant birds, the vampire maggot starts a day-night cycle. The maggot will stay at the bottom of the nest during the day to protect itself from the elements, and from being eaten by the parent bird. At night, it comes up from the bottom of the nest and attaches to the infant birds, sucking their blood. When day comes, it goes back down to the bottom of the nest, and the cycle repeats.

At the same time that the infant birds grow feathers and fly away from the nest, the maggots enter a state of pupation, emerging from the nest one to two weeks later as adult blowflies.

Though they are not harmful to areas where they are native, such as Ohio, bird blowflies can cause damage in areas where they are not, such as the Galápagos Islands. To help control blowfly populations abroad, the Avian Parasitic Fly Project is developing methods for population control. Those methods focus on taking advantage of the flies’ eyesight.

“If you can imagine a picture of a fly, and try to imagine their face in your head, 70 percent of their face, and in some flies even more is taken up by their eyes,” Brodie said. “With flies, it is mostly visual, whereas with most other insects it's going to be olfactory, or smell.”

The first method for population control involves a process called flashing wing beat frequency. That process plays a part in the reproduction of the fly. Essentially, a male blowfly will identify a female blowfly by counting how often light reflects off it in the span of one second. A virgin female blowfly turns its wings in a figure eight pattern 164 times per second; that means it creates 164 flashes of light per second. When a male fly sees that precise amount of flashes, it will assume it’s found a mate.

Using that information, the researchers are testing a device that can replicate the flashing wing beat frequency of a female blowfly. When put in place, the device will attract male blowflies (and sometimes female blowflies) toward it. In that way, researchers can directly interact with blowfly population.

The second method of visual communications for blowflies involves their infrared eyesight. It is assumed that blowflies target specific nests by the concentration of infrared wavelengths that nest emits. For example, if a nest has a low concentration of infrared wavelengths, the fly will assume there are no potential hosts and move on. If a nest has a high concentration of infrared wavelengths, the fly will assume there are potential hosts and plant its eggs.

Given that knowledge, scientists think by placing infrared blocking cloth around the nest, it would possibly prevent the blowfly from finding the nest, thereby protecting the nest.

Studies for the project are done in the lab and the field. Lab experiments involve testing how the blowflies respond to stimuli such as the light-emitting device. Field experiments are the lab experiments done on a natural population.

The project has received attention, garnering support from both the Columbus Audubon and the Sindisa Fund . Madeline Sudnick, a sophomore studying biological sciences, is a central member of the project team and has won the David R. Osborn Award at the Ohio Avian Research Conference for best student presentation for a poster showcasing her involvement.

“I love being a part of this project because I’m at the intersection of so many different aspects of scientific research,” Sudnick said. “I have a foot in ornithology, I have a foot in entomology, and I also get to work with citizen scientists. Their contribution is really helpful, and its important to involve the community like this.”


Development by: Midge Mazur / For The Post

Landing Page

Special Projects

This story is part of a series of specially designed stories that represents some of the best journalism The Post has to offer. Check out the rest of the special projects here.