filter a continuous form (VBA)

I have a continuous form with thousands of rows, but I want to filter that down to just a few rows with a term I am searching for.  Dropping this code in the after update event will accomplish that.  Enjoy!

'Put this in the afterupdate event
Private Sub Searchbox()
Dim a As String
'states that if searchterm is null then return all. if it is not null, the return a wildcard of whatever the search term is
'update the searching for, below, to what the field that the searchterm is going to search
If Not IsNull(Me.searchterm) Then a = a " AND searching for LIKE '*" & Me.searchterm & "*'"
End If
'do not change below this line
If a = "" Then
' No filter required
Me.Filter = ""
Me.FilterOn = False
' Add filter to form
Me.Filter = Right(a, Len(a) - 4)
Me.FilterOn = True
End If
End Sub