Medium Density Fireboard (or MDF) is essentially a fake wood created by mixing glue and pulped wood. This mixture is then pressed into the shape of wood. This wood-glue-mixture that makes up MDF (Mixed Density Fireboard) typically has too much glue to be particularly attractive to termites.
But, termite have been known to nibble on MDF but not much more beyond exploratory behavior. Presumably, the high glue content in MDF repels termites to some degree.
You may be thinking “So that sounds great then, this should be great to use for trim in my new home!” And that would be rational thinking but here’s were things get a little strange.
Is Medium Density Fireboard (MDF) a good idea?
You actually want wooden trim that termites love to eat. The reason being is that the trim in you home is easily visible. This is something that you see everyday and that you can take a closer look at when cleaning up around the house. With termites, the earlier you detect the problem the easier and cheaper it will be to deal with.
What kind of wood should I use for trim in my new house?
Termites prefer to burrow and create their colonies within the walls of a piece of lumber. Termites can create their tiny tunnels for months or years within a pice of wood before there are any visible signs of them. So we do not want termites to skip MDF trim and move on further into the wall to the studs that we cannot see.
This is why it is better to use natural wood trim so that the termites will focus on that prior to moving deeper into your walls and feeding on the structural wood of your home. Ideally you do not want termites in your home at all. But if they do get in somehow, you want to be able to detect their presence far before they establish a serious colony.
Because of this it would be better to stick with solid timber trim so you can detect termite frass, pinholes, or conduct tap tests along your trim more easily. It is also not uncommon for people to bump infested wooden trim with a vacuum cleaner to see it dent quite easily. This is why it is best do go with solid trim instead of MDF trim.