South America
Alligatorweed (Alternanthera philoxeroides)
Eggs are cylindrical and pale yellow at first, but the head capsules of larvae become visible when they are close to hatching. Larvae are yellow initially, turning dark gray or nearly black as they age. Larvae can be up to 6 mm long and have brown or black head capsules. Pupae are cream-colored initially but darken with age. Adults are 4–6 mm long and black with four yellow-gold longitudinal stripes (two on each elytra). Adults have enlarged hind femurs, enabling them to jump large distances. Females are slightly larger than males.
Adults emerge in early spring and begin mating and ovipositing; females lay an average of 1,100 eggs during their lifetime. Eggs are deposited in two rows (12–54 eggs per cluster) on the undersides of alligatorweed leaves. Larvae feed on leaf tissue, often leaving transparent feeding “windows”. Larvae develop through three instars prior to chewing into alligatorweed stems. Pupation occurs within the plant stems. Adults emerge and feed on alligatorweed leaves and stems. There are 4–6 generations per year. Last generation adults overwinter among roots and stems of alligatorweed along water body margins.
Larval and adult feeding on leaves and stems is often severe, leading to eventual submergence of the floating mat and clearing waterways.
Harms, N.E., I.A. Knight, and P.D. Pratt. 2022. Alligatorweed Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2022-25-ALLIGATORWEED-A. https://bugwoodcloud.org/resource/files/23221.pdf