Re: HOW DO BLOW FLY MAGGOTS RESPOND TO LIGHT ?

Dear Andrena,

Blow flies are shiny green and blue flies belonging to the family Calliphoridae. See this site at UC Berkeley for a big picture of the adult, plus descriptions on identifying a blow fly. Pictures of other species can be found at this site. The larval stages of these flies prefer feeding on any dead animal tissue. They can, however, grow by feeding on other food sources.

While I couldn't find a publication describing the reaction of blow fly maggots to specific frequencies or intensities of light, there are a few pieces of information which might help you. Most immature insects avoid light. Since fly maggots are soft bodied, they risk drying out, plus are subject to greater predation, if they go out into the day. Therefore, most the larvae hide from light. Where do they hide? Usually they hide close to their food source.

Since blow fly larvae feed on dead animals, they spend the vast majority of their time on the inside of a corpse. When they have matured, the larvae leave the corpse and enter the soil or leaf litter where they search for a protected place to pupate. It is likely that other signals, such as moisture, play a more prominent role in keeping the maggots out of the light than the light itself.

Studying the behavior of insects which avoid light can be very difficult for a scientist. One solution I have used is to light the laboratory with only red light while observing behavior. Most insects (but not all) can not perceive light frequencies in the red spectrum. Of course the insects can also sense heat from the light source, plus any sounds or other vibrations caused by the observer, so there are many other things to consider when trying to watch insect behavior.

Because blow flies will grow in any available dead animal tissue, they have been valuable in the fieled of forensic entomology. Forensic entomology is the science of determining factors about a human death based on the species and age of insects that come to live within the body. For more information on this fascinating topic, check out this site.

Of course, the maggots have also been used to help humans while living. Before the wide-spread use of antibiotics (and even sometimes today), severe wounds were treated with blow fly larvae. The maggots would eat away the dead tissue preventing it from becoming a source of bacterial infection. Once the dead tissue had been eatten, doctors would remove the maggots, leaving only living tissue behind. See another MAD Scientist's description of this procedure.

More specific biological information about one species, the hairy maggot blow fly, can be found at this link to the University of Florida.


I hope this information helps you, and thank you for your question!

John