The cornicle (or siphuncule) is one of a pair of small upright backward-pointing tubes found on the dorsal side of the 5th or 6th abdominal segments of

aphids Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

. They are sometimes mistaken for cerci. They are no more than pores in some species. These abdominal tubes exude droplets of a quick-hardening defensive fluid''Aphid'', Henry G. Stroyan, McGraw-Hill Encyclopedia of Science and Technology, 8th Edition, 1997, containing triacylglycerols called ''cornicle wax''. There is some confusion in the literature about the function of the cornicle wax secretions. It was common at one time to suggest that the cornicles were the source of the honeydew, and this was even included in the ''

Shorter Oxford English Dictionary The ''Shorter Oxford English Dictionary'' (''SOED'') is an English language dictionary published by the Oxford University Press. The SOED is a two-volume abridgement of the twenty-volume ''Oxford English Dictionary'' (''OED''). Print editions ...

'' and the 2008 edition of the

World Book Encyclopedia The ''World Book Encyclopedia'' is an American encyclopedia. ''World Book'' was first published in 1917. Since 1925, a new edition of the encyclopedia has been published annually. Although published online in digital form for a number of years, ...

. There also is documentation in the literature for cornicle wax luring predators in some cases.

References

Aphids Insect anatomy {{insect-anatomy-stub