Insect eggs: Julia Heliconian Butterfly
In the top photo you can see an egg of the commonly named Julia Heliconian, Dryas iulia (Nymphalidae), perched on the tendril of a Passiflora plant. The second photo shows an adult of this species.
Like most other Heliconiines, the Julia Heliconian lays it’s eggs on Passiflora (Passion flower). There has been a great deal of study into the relationship between these plants and Heliconiine butterflies, which strongly suggests they they co-evolved.
There is a constant evolutionary battle in which the plants try to defend themselves from the butterflies. Some Passiflora vines produce false stipules at the base of leaf stems, that induce egg laying by certain Heliconiinae species. A day or two later the stipules drop off, carrying the eggs with them. Eggs which fall to the ground probably get eaten by ants, but even if they survive, the resulting larvae will starve. Certain other Passiflora vines produce tiny tubercules on the stipules that mimic Heliconiine eggs. Any butterfly visiting the plant sees the false eggs, is misled into thinking that the plant is already overladen with eggs, and is consequently inhibited from ovipositing.
The dazzling orange Dryas iulia is widespread and common in the southern United States, Central America and much of the Caribbean, and occurs throughout all of the tropical and subtropical areas of South America.
Technique (egg): Colored Scanning Electron Microscope image.
Photo credit: [Top: ©Martin Oeggerli] - [Bottom: ©Richard Stickney | Locality: Surinam, at the NC Museum of Life & Science, Durham, North Carolina, US, 2013]