I am not sure where thy come from or what family of insect they are. The best defense would be to enclose the whole flute case in a tightly sealed plastic bag if you are going to store the flute for a long time. If you do discover them I would suggest you replace the case with a new one. Gross, isn't it. Click here for the manufacturer's link page .
Word of mouth is the best, or call a local music school, conservatory, orchestra, etc.
No commitment, just try another teacher. There is also a music teacher locater home page. I have not used it much but to visit it, click here. No one makes a left handed flute. The reason is when you play in an orchestra or band all the flutes must face the same way.