What have your favourite celebrities been up to this past week and weekend? Well, we'll tell you.Cara Delevingne attended the People's Climate March event and she appeared to be dressed up in an animal costume, of course. Although what kind, we're still a little unsure of.Other models, such as Kendall Jenner and icon Naomi Campbell were still rocking the runway in Milan at fashion, with both sharing snaps from their respective trips (just check out Kendall's delicious ice cream picture).Over in LA, Jessica Alba posted an adorable photo of her two little girls having a picnic in the garden. And speaking of cute, have you seen Dasiy Lowe's dog? It's quite possibly one of the sweetest dogs we've ever seen.Other pictures of note includes Lena Dunham's 'sweaty' onesie, Stella McCartney and an oversized pretzel (which we really want to eat), and Alexa Chung's throw back photo from when she was just 19.But without a doubt, our favourite celebrity photo comes from the King of Instagram, Jared Leto, who poked fun at the rumours he's a vampire because he looks like he doesn't age.No seriously, we know he was joking but what is his secret?

Reese Witherspoon, Stella McCartney and Daisy Lowe in this week's cele

Cara Delevingne attends climate change march

Joudan Dunn's homage to Kate and Naomi

Kendall Jenner eats some amazing ice cream while at Milan fashion week

Jessica Alba's little girls' back garden picnic

Naomi Campbell and make-up artist Pat McGrath

Lena Dunham reveals the glamour of hotel trips

Mindy Kaling shows off some awesome stationery

Stella McCartney has a giant pretzel (which we'd like to eat please)

Daisy Lowe with the cutest dog ever

Alexa Chung shares throwback picture

Poppy Delevingne hangs out with all the beautiful people in Milan

Jared Leto jokes about his youthful good looks

Allison Williams posts cute snap of GIRLS cast

Reese Witherspoon hangs out with her mum

Lady Gaga on top of a piano. Casual.

Reese Witherspoon, Stella McCartney and Daisy Lowe in this week's celebrity Instagram round-up

The best of the A-list pics in this week celebrity Instagram round-up