holes along top of hardie siding board? (light, cold, caulk)

[christiner81]

I'm in the process of re-caulking seams in my hardie siding (15 year old house) and noticed there are holes drilled along the top of one of the rows all around the house. It's about 3 feet off the ground. I don't see a purpose for this and am a little worried that water has been getting in these holes. Is there ever a good reason to have holes like this??? If not I will caulk them all.

[harry chickpea]

Probably an attempt at extermination of bugs. Go ahead and do a light caulking. If you or an exterminator need to come back and re-use the holes, just push the caulking out of the way. Asian lady beetles like to get in behind that type of siding around the first real cold snap of fall. At that time or just prior to that, a spray of the proper insecticide can act as a barrier. Otherwise, they are annoying but harmless pests all winter.