Fig 1.
Leaf clipping by tree-feeding caterpillars on excised stems.
(A-C) Final instar Datana angusii (Notodontidae: Phalerinae) severing the midrib of a pecan leaflet (Carya illinoinensis, Juglandaceae), then applying saliva to the midrib stub (D). (E-G) Final instar Cecrita biundata (Notodontidae: Heterocampinae) similarly clipping the petiole of a water oak leaf (Quercus nigra, Fagaceae) before secreting saliva onto the petiole stub.
Fig 2.
Final instar of Datana integerrima (Notodontidae) clipping a pecan leaflet in the field.
The larva clipped the pecan midrib (Carya illinoinensis, Juglandaceae), then backed up and clipped it again repeatedly for a total of seven clips in eight minutes. Each clip was approximately one cm closer to the base of the leaflet.
Fig 3.
Intact and cauterized final instar larvae of Symmerista albifrons on white oak (Quercus alba).
(A) Intact larva with a petiole that it clipped and bathed in red saliva. (B) Larva with a cauterized spinneret that just severed the petiole and is wiping its mouthparts on the stub. No red fluid is visible because cautery blocked the opening of the labial glands preventing release of saliva. Intact (C) and cauterized (D) larvae feeding after chewing a furrow in leaf veins. Red saliva is visible only on the furrow cut by the intact larva.
Fig 4.
Labial salivary glands of Symmerista leucitys.
(A) Head capsule and attached labial glands of a final instar. (B) Head capsule of a prepupa with paired labial glands that secrete the silk used in constructing a cocoon. (C) Head of a final instar with a close-up of the spinneret (D). (E) Juncture of the thin and thick portions of a labial gland from a final instar. (F) Thin portion of the labial gland from a final instar discharging its red contents after being severed. Scale bars equal 0.5 mm in C, 0.1 mm in D, and 0.3 mm in E and F.
Fig 5.
Petioles of sugar maple (Acer saccharum) with xylem stained by Symmerista leucitys saliva or dye.
(A) Petiole clipped by a S. leucitys larva, then severed with a razor blade 2.5 mm from the stub tip approximately five minutes after the larva finished applying saliva. The red salivary pigment moved into the petiole staining the xylem. (B) Petiole xylem stained by safranin O dye (0.2%) pulled up the xylem by transpiration. (C) Petiole stub treated with 1μl safranin O dye (0.2%). After 5 minutes, the petiole was severed 2.5mm from the initial cut. The dye moved in a retrograde direction down the xylem staining the same tissues as Symmerista pigment in (A) and dye in (B). The petiole slices in A-C were photographed dry to prevent pigment and dye from dissolving or spreading to adjacent tissues. (D) Thin slice of petiole stained with toluidine blue followed by safranin O to show the location of xylem and phloem. Scale bars equal 0.2 mm in A-C and 0.5mm in D. The dorsal surface of the petioles is on the right side.
Table 1.
Time that caterpillars in 34 species spent clipping leaves and applying saliva.
Table 2.
Time that non-clipping caterpillars spent applying saliva to petiole or midrib stubs.
Fig 6.
Furrows, girdles, and petiole crimps of final instar notodontids.
(A) Heterocampa umbrata larva feeding on southern red oak (Quercus falcata) after chewing a furrow in the midrib. (B) Datana integerrima larva feeding on a pecan leaflet (Carya illinoinensis) near a girdle that it cut in the rachis. (C) Cecrita guttivitta larva feeding near a furrow in a Carya illinoinensis leaf. (D) Peridea angulosa crimping the petiole of a water oak leaf (Quercus nigra).