Ants can get sugar to supplement their diet by tending aphids and collecting honeydew. The honeydew is a waste product for the aphids who gain protection from aggressive ants at little cost. Ants recongize aphids by the lipids present on the aphid cuticle. Ants tap aphids and other moving insects with their antenna. An insect that lacks the proper odor may be attacked and foricbly removed from the area.
Lacewings are predators of aphids and other soft bodied insects as larvae and adults. The larvae have limited mobility. Large groups of aphids are difficult to find and they are often guarded by ants. How to get past the ants?
Larvae of the green lacewing, Mallada desjardinsi, feed on aphids, then attach the carcasses to their backs. A group of scientists* tested this strategy as a defense against ants. They observed lacewing larvae with and without aphid carcasses. Those with aphid caracasses were attacked less frequently than those without. They removed lipids from aphid cuticle and allowed lacewing larvae to place the carcasses on their back. If aphid carcasses did not contain lipids, lacewings were attacked by ants with a much greater frequency. They then treated cotton wool with aphid lipids and presented it to lacewings, who placed it on their backs. The lacewings with the cotton wool coated with aphid lipids were attacked much less frequently than those with untreated cotton wool. This series of experiments is strong evidence that ants can recognize cuticular lipids of aphids, and that the aphid carcasses can provide protection for lacewing larvae. A wolf and sheep’s clothing is only a fable. A lacewing in aphid clothing is a real thing.
Masayuki Hayashi, Yasuyuki Choh, Kiyoshi Nakamuta & Masashi Nomura. 2014. Do Aphid Carcasses on the Backs of Larvae of Green Lacewing Work as Chemical Mimicry against Aphid-Tending Ants? J Chem Ecol. 40:569–576.