VBA Summing across rows and columns

I'm hoping to come up with a formula/program to handle the following data:

Using column A, I want to sum the associated values found in columns B and C for BS rows and subsequent US rows until the next BS row comes up. There is always one BS value, but anywhere from 0-4 US values. If the SUMed values could be placed in column D that would be great!

Here is a simplified example of what my sheet looks like, I have added the 4th Total Egg Sum column - these are the numbers I'm trying to get without having to individually calculate each sum.

Excel Forum Help.xlsx

Any help is much appreciated! Thanks!

Thank you so much!! That worked great!