He scored one probable He111 on 16May und four kills on 5Jun1940.
His 16May kill might have been upgraded to confirmed later, because the SHAA credits him with 5 kills and no probables.
This website also indicates 5 individual confirmed kills:
http://estouteville.ecalles.free.fr/...H/dietrich.htm
16May kill was scored in the Bloch MB.152:
http://aviateurs.e-monsite.com/pages...dietrioch.html
His 5Jun kills, too:
http://www.cieldegloire.fr/gc_2_10.php
That makes him one of only two Bloch MB.152 aces, the other being Robert Thollon.