Two sawfly galls (Pontania sp.) on the upper surface of a willow (Salix lasiandra) leaf in central Washington. Photograph by K. Ernest.
Sawfly galls (Pontania sp.) as they appear on the under surface of willow (Salix lasiandra) leaves in central Washington. Photograph by K. Ernest.
Legend: A “successful” gall has an exit hole chewed by the sawfly larva at the end of its development within the gall. Photograph (Pontania sp. in Arizona) by Karen M. Clancy.
Legend: Sawfly (Pontania sp.) adult on willow leaf. Females lay their eggs into leaf tissues, where the developing larva will live and feed within a gall. Photograph by Karen M. Clancy.
Legend: Sawfly (Pontania sp.) larva inside a gall. Note the external parasitoid larva (translucent white) attached to the dorsal surface of the sawfly larva. The small orangish dots are sawfly frass (feces). Photograph by Karen M. Clancy. [note to editor: also link this to the description of the larva in the 3rd paragraph of the Introduction section of the Detailed Description of the Experiment]
Legend: Galls initiated by sawfly larvae, but then aborted (unsuccessful) contain a mass of mostly undifferentiated tissue with no hollow in the center. Photograph by Karen M. Clancy.
Legend: In contrast to aborted galls, active galls are hollow inside because the larva is consuming tissue and the tissue is more organized. Photograph by Karen M. Clancy.
Feel free to use the PDF's linked above, whole or in part, to tailor an unique handout for your students. Here are two contrasting examples: