The invasion has begun...

Shadflies take over this parking lot on the corner of Oak and Fraser Tuesday morning.  PHOTO BY CHRIS DAWSON.

Power hoses were out in full force in downtown North Bay Tuesday morning as the first wave of the annual Shadflly invasion began Monday night and into Tuesday morning.  

Public works crews were busy before 9 am sweeping and spraying off the stinky bugs off the downtown city streets.  

It's about the right time as the Shad's usually make their way out of Lake Nipissing in late June and early July.  

If you don't already know the smelly bugs have no mouths and are harmless. The bad news is for fishermen, as the Shad's make for a tasty fish treat and with the bugs coming out in masses, it's a buffet that area fish don't miss out on.    

The good news is that a good crop of Shadflies is an indication of a healthy Lake Nipissing.  

Some North Bay residents even avoid the waterfront this time of year because they claim they are allergic to the bugs.  

Why do they come in swarm? 

The swarms of Shadflies or Mayflies as they have also been called, have been reported to be so large that they can be seen on doplar radar.  

But why do they come out in the millions?  According to Science North's Bruce Doran its because the flies are not good flyers and can't escape predators.  

"They have evolved a strategy to 'evade' predators," said Doran. 

"The adults will time their emergence at the same time so that millions of them will appear. This essentially overwhelms predators, which cannot eat all the mayflies, and therefore many of the insects survive

"The role of adult mayflies is to mate and lay eggs before they die. In fact, adult mayflies do not have mouthparts and die several days after they have emerged."