Boston Ivy

My mum has asked me to ask a question...

She has a very large Boston Ivy growing along the front fence. Last year, at this time, part of it died. She removed the dead part and for the rest of the year it grew okay. The same thing has happened this year.... Anyone know why?

I wondered if maybe there was some kind of ground bug that comes out in spring that killed it?

Thanks,

GillyP's Mummy