The botanical name for erukkum (erukkan, erukku) is *Calotropis gigantea *and
for vellai erukkan it is *Calotropis procera. *Both belong to the family
The common names are Giant Milkweed and Sodom's Apple (West Asia).
Painted grasshopper feeds on Erukkam (C. gigantea & C. procera ) leaves.
Plain tiger butterfly(Danaus chrysippaus) lays eggs on Erukkam leaves. Log
on to the link given below & read more.
Infact both are native Indian Sps. the difference is
C.gigantea flowers are White to purple, rarely light green yellow or white. Flowers not scented where as C.procera White to pink, scented.
Another difference is C.gigantea generally grows up to a large size (8 to 10 ft) while c.procera is shorter and grows up to 3 -- 6 ft.