The egg is small, milky white, longer than it is wide, and has a
slight constriction in the center. The larva is green to white and
about 1/4 inch long when full grown. The larva pupates in the mine
between the leaf tissues in a reddish-brown puparium. The adult
is a gray to brown fly slightly more than 1/4 inch long.
on image for larger version
1. Corn Blotch Leaf Miner
This insect apparently winters as a mature larva or pupa in
a puparium. In the spring the adults emerge and within 5 to
10 days begin to insert eggs in either the upper or lower leaf
surface of corn or one of the broadleaf millets. Females may
lay 100 or more eggs during their life span. The larvae hatching
from them tunnel in the leaf tissues, leaving mines or transparent
galleries. Often many mines appear on a single leaf. The larvae
pupate in the leaf tunnel and emerge as flies in two or three
weeks. From four to six weeks are required to complete the entire
life cycle. Thus there are probably three to five generations
The damage done by this pest is believed to be of little or no economic
importance. The leaf mining seldom consumes a very large portion
of the leaf, and only a few leaves per plant are usually involved.
Likewise,feeding and egglaying punctures probably have little effect
on plant vitality.
Susan T. Ratcliffe (firstname.lastname@example.org)
Michael E. Gray (email@example.com)