The forest tent caterpillar is on its way to Thunder Bay.
Local entomologist Ken Deacon said the insect is out west taking up residence in the Dryden area so the invasion in the city will happen next year, although there signs some of the bugs have already arrived.
It's not all bad news as the tent caterpillar is a native species and a population explosion every 10 to 12 years is normal.
"This is right on schedule," said Deacon Friday at the Thunder Bay District Health Unit.
And while the tent caterpillar, commonly mistaken as an army worm, will reach abundant numbers next year, Deacon said it's a friendly fly.
"It lands on you, walks around, sticks out it's big tongue, licks you," he said.
But that friendship doesn't extend to other caterpillars.
"They lay their eggs in the caterpillars and it actually burrows into the caterpillars and eats the caterpillar from the inside out, so end of caterpillar," said Deacon.
The caterpillars arrival will mean that the trees will be bare.
"It's going to look like wintertime in July," Deacon said.
However, the healthy trees will survive.
"The deceased trees, the unhealthy trees may be killed because of the stress," added Deacon.
The forest tent caterpillar is named so because in it's early development stages, the eggs hatch and the larvae use the silk to create tents in the crooks of trees.
If residents really want to protect their trees, the best time to act is when they see one of those tents in their trees.
Soap and water is best to get rid of it, said Deacon, noting pesticides aren't necessary when the tree, if healthy, will easily survive the invasion.