What is causing very fine saw dust and sticky drops under Mimosa tree

Question

Mimosa dust I have a Mimosa tree over my driveway.  Every day there is a fine sawdust like substance on my car along with very fine droplets of a sticky substance which attracts flies.  This started before the flowers appeared an is continuing even with the seed pods on the tree so I don't think it is nectar.  I do not see any insect holes.  I had this problem to a much lesser extent in the past few years.  What can this be.  The tree is about 12 yrs old and about 30 feet high.

Thank you so much for you time.

sincerely, Joseph Lacey

Answer
Joseph:
I would be very suspicious of an insect associated with the sawdust material and sticky drops on your car.  If indeed the material is sawdust, then it may from an insect boring into the wood.  They are probably "scratching" or digging out the wood and it is dropping on your car.  The sticky stuff is probably "honeydew" or insect poop.  This honeydew is clear/sticky and sweet- which is probably the reason it attracts other insects since it is high in sugars etc. Aphids are one of the most common producers of this material honeydew.

Steve