Wrap divs inside the parent div using jquery

Question

I'm trying to get the below divs under one div in count of 3 using jquery and store it in separate variables to append them after a specific div in the DOM but not sure how to do it. Please help!

<div class="catalog-items">
  <div class="collapse" id="a1"></div>
  <div class="collapse" id="a2"></div>
  <div class="collapse" id="a3"></div>
  <div class="collapse" id="a4"></div>
  <div class="collapse" id="a5"></div>
  <div class="collapse" id="a6"></div>
  <div class="collapse" id="a7"></div>
</div>

Thanks,