DESCRIPTION OF THE PEST
The lesser canna leafroller (Geshnacannalis)
is the larva (caterpillar) of the lesser canna leafroller moth. The caterpillar
ranges in size from 1/16 inch when newly hatched to 7/8 inch when mature. As it
matures its body changes from cream to greenish in color, but its head remains
The leafrollers survive the winter in rolled,
dead leaves of the canna. They mature to adults, which appear in the spring.
Adult females lay their eggs on the canna. Initially the tiny, newly hatched
caterpillars tunnel inside the leaves between the upper and lower surfaces.
When they become too large, they exit to the upper leaf surface where they
fasten edges of leaves so that the leaves cannot unfurl or they can roll one
edge of an already open leaf. While in this protected area, they generally feed
on the leaf`s upper surface but will also bore through the rolled leaf.
Infested leaves often have several holes through them. Heavily infested leaves
may not open at all and the plants may fail to bloom. When fully mature, the
caterpillars spin a cocoon where they transform to adults. More than one generation
occurs per year.
Since the caterpillars overwinter in the canna
leaves, removing and destroying above ground plant parts in the winter will
reduce numbers of this pest. For severe infestations, sprays with a foliar
systemic insecticide, such as acephate, will kill the borers within the leaves.
One or two sprays may be sufficient. The natural insecticide, Bacillus
thuringiensis (Bt) will control the leaf rollers if sprayed 3 times
at weekly intervals when damage is first noticed. Spray Btin the
evening, and spray into the rolled leaves if damage is advanced.
Control of Flowering Bulb Insect Pests (Acephate –Bifenthrin
–Permethrin –Cyfluthrin )