About this tool
An identification guide for polyphagous and cosmopolitan aphids
Aphids are one of the most important agricultural insect pests. Members of the family Aphididae (Sternorrhyncha, Hemiptera), aphids are sap-sucking insects that are most common in the temperate zones of the world.
They cause direct feeding damage to the plant and serve as vectors of plant viruses. In addition, aphid honeydew
promotes the growth of sooty mold and attracts nuisance ants. Many economically important aphid species have a worldwide distribution but some remain outside the USA. The establishment
of these aphid species would present dire consequences to US agriculture, as happened recently with the advent of the soybean aphid. In order to make informed decisions about the importation
of agricultural products, it is critical that intercepted aphids be accurately identified. AphID is the latest tool in the USDA's means to identify potential aphid pests.
AphID is intended to help US port identifiers, quarantine officers, and anyone seeking a preliminary but relatively simple way to identify aphids. A total of 66 aphid species are treated.
AphID includes the 38 polyphagous aphid species in the three seminal works by Roger Blackman and Victor Eastop (1994, 2000, 2006). The remaining aphids represent the 28 species most frequently
intercepted at U.S. ports of entry that are not already represented on the Blackman & Eastop list.
The key has 132 end points, one for each alata (winged female) and aptera (wingless female) of each of 66 species. The key will work for slide-mounted winged and wingless adult live-bearing females only.
The key does not include males, oviparae (egg-laying females), or immatures.
It may not work for all fundatrices (foundress from the first egg) or alatae and apterae from primary hosts (for those species with host alternation).
The content of this tool has significant limitations! Please read the information below carefully in order to understand exactly how the key is constructed and to avoid misidentifications.
Limited number of species
The number of aphid species addressed in this tool is only a small percentage of the world aphid fauna which consists of several thousand species. Therefore, there is a chance that your aphid specimen
may key to a species that is not the correct match. For example, Anoecia setariae apterae (not included in the key) could be mistakenly identified as Cinara
confinis depending on the characters selected. All identifications should be compared to the species pages and an authoritatively identified reference specimen for further assessment.
Limited number of morphs
Aphids come in a great variety of morphs. Some species are known to have over a dozen morphs, and the vast majority have at least five: fundatrix, aptera vivipara,
alata vivipara, ovipara, and male. Certain morphs of many species are not well studied. Additionally, aphid nymphs are also not well characterized and are often exceptionally hard to
identify. The identification key is only useable for adult aptera vivipara and adult alata vivipara specimens. In some cases, a fundatrix (a special form of vivipara) will also key correctly.
However, any other morphs or developmental stages are unidentifiable with this key. It is critical that you first confirm that your specimen is an adult vivipara before using this key.
Limited number of specimens
Aphid species identification uses many continuous characters and ratios and as such this key will require you to make many measurements. Also, aphid individuals
of any given species come in a wide range of sizes and proportionality. The identification key includes many continuous characters, all of which include two ranges: one estimates the
maximum and minimum possible lengths, counts, or ratios for a species; the other estimates the most likely lengths, counts, or ratios. The accuracy of these character range estimates
is limited by the number of specimens that were measured in preparing the key. Ideally, specimens of all possible sizes and proportions would be measured.
As this ideal is unrealistic, please be aware that the specimen you are examining may be unusual in size or proportion and thus cannot be identified correctly.