Plant Parasites of Europe

leafminers, galls and fungi

Openings in the mine

exit slit

Each mine must at some moment be vacated by its occupant. The opening that is made then often has a very constant shape. In those Agromyzidae species where the mine is left prior to pupation, the larvae make neat semicircular exit slit in the epidermis.


Agromyza alnivora on Alder: exit slit

upper- or lower-surface

Often it is a constant feature of a species whether its exit slits are made in the upper or lower epidermis. In Phytomyza minuscula, a species with an upper-surface mine, the exit slits are invariably in the lower epidermis.

In Stigmella-species the exit slit is more highly arched; here too the the position of the exit slit often just as constant as that of the egg.


Phytomyza minuscula on Lesser Meadow Rue: lower surface exit slits


Most mining larvae spend their entire life within a single mine. There are, however, species that are capable to move to another (part of the) leaf and start a new mine. An odd species goes ‘through the house’, tunnelling through petiole, stem and petiole to a new leave. Most actually leave the protection of the mine, and bore themselves in elsewhere. With a bit of luck it sometimes is possible to see the opening that is made by the larva while reentering.

Many species lack the possibility to reenter a leaf: bracing yourself firmly, gnaw a hole in the epidermis and bore yourself in often goes beyond the capabilities of a larva.


Mompha raschkiella on Fireweed: opening

election of frass

Openings in the mine often have the principal role to enable the ejection of frass.

Last modified 1.viii.2017