Say What? phor·e·sy ( /ˈfôrəsē/)
Several years ago our Plant Health Care department noticed how despite some rooftop plants being totally isolated and
never coming in contact with other plants (especially new ones) suddenly got insects. We were perplexed and decided to
investigate. That’s when we learned about this very odd form of insect dispersal called PHORESY.
Phoresy is simply when one organism attaches itself and then travels on another without hurting it. It is a form of
association where there is no parasitic relationship – It means literally “eating at the same table”. Basically they are
hitching a ride for free!
As we researched more were were fascinated by the complexity of this phenomenon and how it actually has been around
long enough that some insects have evolved physical traits to enhance this method of transportation. We also discovered
several of the insects we noticed that were popping up in our gardens had these evolutionary adaptations or were using
this method to get around. Take a look at the hooks used for grabbing on the feet of some mites!
Flower mites are wingless but use foraging bees to travel to new flowers. When the bee enter a flower to collect nectar or
pollen the mites climb on – when it reaches the next flower – the mites climb off ! – You tube picture below.
Scale crawlers ( a just hatched stage of scale insect) attach themselves to other insects by means of sucker parts on their
legs ( are you imagining the movie Alien at this point ) and drop off once they arrived at a new location. Talk about evolution !!!!! See this high powered magnification from
the California Avocado Commission.
Some beetle larvae cling on to wasps and hitch a ride to the next bit of greenery. And mites will also latch on to a
centipede then get off at the next available plant! ( crafty right !)
It is not just insects that do this but it has been shown to occur in “fire blight” a disease of apples and pears caused by the
plant pathogen Erwinia amylovora. The bacterium is picked up on the feet and mouth parts of bees and flies when they
visit flowers on diseased trees, and then are carried on to to healthy ones. The blight can be lethal to trees.
No worries garden people ! We here at Plant Specialists are aware of these tricky methods and have a battery of methods
to control and deal with both insects and diseases. We have a whole department dedicated to it – Plant Health Care.
Any of you uneasy with pictures of bugs ? Then I strongly discourage you from Googling on the subject ! Some of the
pictures are downright scary.
Story courtesy of our resident horticulturalist – Peter Morris