Termites in tree?

[canberraben]

Hi all 

My wife just cut down this small tree in our backyard and noticed that the tree is hollowed out and there seems to be the remnants of termites or ants or some other sort of bug. 

Wondering: 

A) can anybody can identify the cause (ie termites?)

B) what would you recommend for pest control? 
C) if it’s worth getting a pest control person out to spray other areas of the house given this tree was right next to a wooden deck/wooden framed house. 

thanks!