 A 10 @-@ year study of the distribution , time of fruiting and habitats of morel and false morel population in Iowa showed that early false morels are the first morels to fruit in the spring , appearing shortly after leaves begin to form on deciduous trees . Narrow @-@ head morels ( Morchella angusticeps ) fruit next , followed by the yellow or white morels ( Morchella esculenta ) , then lastly Morchella crassipes . The fruit bodies serve as a habitat for breeding dipterans ( flies ) , including Porricondyla media , Pegomya geniculata , and Trichocera annulata . 
