Zombie Bees

The confirmation of the phorid fly in a beehive on Vancouver Island is nothing more than an academic curiosity. It doesn’t pose a serious threat to our honey bee population. 

The Phoridae , a super family of the Diptera (Flies) is comprised of thousands of species distributed through most of the world. Most are scavenger that feed on rotting plant materials, fungal mycelia, cadavers, etc. Only very few are actual insect parasites.  A. borealis is one of those species that predates on some bee and wasp species. An adult fly will lay an egg on the cuticle of an adult bee. The egg hatches and tiny larva will break through the host cuticle and then start feeding on the tissue of the host. Successful larval stages will occur, followed by a pupal stage and then eventually the adult phorid fly will emerge. Of course by that time, the poor bee is pretty sick and disoriented (~appearing as a zombie). It is interesting to note that this method of predation is almost universally employed by solitary wasps throughout the world; hence their importance of controlling insect populations in the environment. 

The Phorid Fly can’t establish a thriving population within the hive. Adult flies will have to seek a host after mating which is not an easy, risk-free task. So, by the end of the day, a colony may end up with a few bees (a dozen?) infected with the phorid fly. But then, any honey bee population is subject to all kinds of threats, of which many are far more damaging. It is also important to remember that a healthy bee colony produces about 1,500 new bees every day while it loses well over 1,000 bees every day. Their deaths could be the result of old age, disease, poor weather, malnutrition, beekeeper mismanagement, etc, including predation in the field. Out in the field, bees may be caught in a spider web, hit by a passing car, caught by a wasp, etc. The phorid fly may be a casual predator that may affect a few bees but there is no evidence to suggest that it will threaten the survivability of the  honey bee colony.