In a post on Wizarding World, Rowling herself explains: "Only a minority of trees can produce wand quality wood [...] It takes years of experience to tell which ones have the gift, although the job is made easier if Bowtruckles are found nesting in the leaves, as they never inhabit mundane trees." So, while bowtruckles are considered largely peaceful, getting between them and their home tree could prove disastrous. Scamander's advice? "An offering of woodlice will placate the bowtruckle long enough to let a Witch or Wizard remove wand-wood from its tree."
It would seem that Pickett has an equally soft spot in his little wooden heart for Newt Scamander, hence his tendency to do the magizoologist's bidding. But poor Pickett will have to wait a little longer to return to the big screen with his pal, as recasting issues and the pandemic have pushed the next Fantastic Beasts release until next year. Production has already paused yet again, as someone on the production team recently tested positive for COVID-19, according to The Hollywood Reporter. Here's hoping Pickett and the rest of Newt Scamander's magical gang make it back soon in good health; it sounds like Redmayne is getting pretty attached to his fantastic friends.