A picture wing fly (Delphinium picta) and an ant (Formica palidefulva) are competing for nectar secreted from the extrafloral nectaries of the Passiflora vine (Passiflora incarnata). This short observation was filmed on August 25 2014. Georgia State Botanical Garden, Athens, GA, USA.
Here we see multiple overlapping natural history stories. A passiflora vine is being defended by workers of a Formica palidefulva colony. A picture wing fly is sneaking around the vine looking for an opportunity to sip sweet nectar from the extrafloral nectaries. They look like playing chase. Ants can bite, sting or squirt formic acid to drive away intruders. The sweet nectar secreted from the nectaries are attractive to both insects.
Picture wing fly is a distinct evolutionary product fooling visual predators such as wasps and jumping spiders. Its defense strategy is being “a sheep in wolf clothes”. The wing patterns are thought to be mimicking a jumping spider, an adaptation for avoiding attacks from predators especially the jumping spiders.
Filmed early-August 2014 in Japan, you can see a different species of this fly, the small picture-winged fly (Pseudotephritis millepunctata, family Ulidiidae) visiting an oak tree (Quercus crispula, family Fagaceae) to feed on fermenting tree sap. You can recognize females of this fly from their black ovipositors. You can see a cautious co-existence with ants and other insects in this short observation. However, at 12 seconds the fly is attacked by an ant:
Visual deception is not limited to the picture wing fly. Extrafloral nectaries of the passiflora look like the eggs of a butterfly. There are two species of butterflies – Variegated fritillary (Euptoieta claudia) and Gulf fritillary (Agraulis vanillae) – who lay their eggs on passiflora vines. Caterpillars emerging from those eggs are cannibalistic. For this reason a female butterfly must avoid laying eggs on a plant that has been visited by another female since it is rather likely that early hatching caterpillars may cannibalize on her eggs. Nectaries that resemble butterfly eggs is an effective way of reducing herbivore pressure by visually deceiving female butterflies.
This short observation was filmed on August 25 2014. Georgia State Botanical Garden, Athens, GA, USA.