Characters for Identifying Common Families of Sternorrhyncha (Hemiptera)1

Home , Aphis pomi, Eriosomatinae, Kermesidae, Pachypsylla, Phylloxera (genus), Psylla

Psyllidae: Diagnostic characters: small (2-5 mm); 2 pairs of wings in both sexes, held roof-like over body, forewing often thicker than hind wing; resemble miniature cicadas; strong jumping legs; antennae 10-segmented; tarsi 2-segmented, with 2 claws.

Psyllids, or jumping plant lice, feed on phloem sap, and are usually very host species speciﬁc; a very few produce galls such as the hackberry nipple gall psyllid, Pachypsylla celtidismamma, and Psylla magnicauda. The nymphs live inside the galls. Eggs laid shallowly in plant tissue and covered with wax. Nymphs do not closely resemble adults and produce copious powdery wax. Adults resemble miniature cicadas and are active jumpers and ﬂiers. Two important pest species, both introduced from Europe, are the pear psylla, Psylla pyricola, and the apple sucker, Psylla mali. Nymphs feed on axils of leaves and fruit and produce copious honeydew on which fungus grows; infected trees shed leaves and fruit. The Asian citrus psyllid, Diaphorina citri, is also causing a serious infection of citrus in Florida, the SE US, and California. It produces a toxin that distorts young shoots and it also transmits a bacteria that affects fruit size and development, making them unmarketable.

Aleyrodidae: Whiteﬂies. Diagnostic characters: minute (2-3 mm); 2 pairs of wings in both sexes; forewings about equal in size to hind wings; body and wings covered with a white waxy powder.

1st instar nymphs are active, but later nymphs are sessile and scale-like. The group is abundant in the tropics. One important species affects citrus - fungus growing on honeydew interferes with photosynthesis. Other species are important greenhouse pests.

1 Photos from BugGuide.net

1 Aphididae: Diagnostic characters: winged or apterous; forewings much larger than hind wings; body pear-shaped; antennae 3-7 segmented; pair of cornicles near posterior end of abdomen. Examples: Rhopalosiphum maidis and Aphis pomi.

Cornicles secrete defensive substance. Some secrete wax. Honeydew secreted from anus. Often milked by ants. Honeydew "rain."

A good discussion of the complex life cycles (heterogamy) of aphids can be found on the Tree of Life website, of which one example is the following:

--Eggs overwinter --Hatch in spring into parthenogenetic female fundatrix, usually wingless, primary host plant --Viviparous birth to wingless females, apterae (several generations) --Birth to winged female, alatae, migrate to secondary host plant --Parthenogenetic birth to several generations of female apterae on secondary host --Produce alatae, migrate back to primary host plant --Birth to male & female (sexuparae), sexual reproduction - oviparous female (ovipara) produce fertilized eggs from which fundatrix hatches.

Enormous numbers can build up. Many serve as important vectors of plant viruses, which cause severe economic loss to crops. Important historical collection and research at U of Minn (Oestlund, Granovsky, Ragsdale).

Aphididae: Eriosomatinae: Wooly and gall-making aphids. Cornicles reduced or absent, profuse wax producers. Adults lack mouthparts. Female produces only 1 egg. Also with complex life cycles. Primary host plant (tree or shrub), secondary host plant (herbaceous). Often produce gall on primary host. Alder wooly aphid is common in Minnesota.

2 Adelgidae: Pine and spruce aphids. Feed only on conifers. Primary hosts (where galls often formed) and secondary hosts, both conifers. Complex life cycles. e.g., eastern spruce gall aphid, balsam woolly aphid

Phylloxeridae: phylloxerans, including the grape phylloxera, Daktulosphaira vitifoliae, an important pest on grapes, especially in Europe. Complex life history. Causes galls on grape leaves and gall-like swellings on roots, with many aphids inside.

Coccoidea:Diagnostic characters: very highly modiﬁed; female wingless, usually legless, sessile; male forewing developed, hind wing reduced to style-like processes, long antennae, long style on end of abdomen, lack mouthparts, do not feed. Complex life cycles. 1st instar nymphs active “crawlers," 2nd instar legs and antennae lost, sessile, waxy or scale-like covering over body. Female remains here. Male develops wings.

Coccidae — Soft scales, wax scales, tortoise scales - many citrus, greenhouse, and house plant pests (brown soft scale); Chinese wax scale - males produce pure white wax for making candles.

3 Diaspididae — Armored scales - Largest family in North America, with very important pest species. Scales from wax as well as cast skins. Very different shapes of scales. Injure plants by sucking sap. San Jose Scale, oystershell scale.

Pseudococcidae — Mealybugs - female body segments distinct, with legs. 300 spp. in North America. Citrus, greenhouse, and house plant pests.

Other coccoid families:

Margarodidae — Giant coccids and ground pearls (large, to 2.5 cm); cottony cushion scale - pest of citrus in West.

Kerridae — Lac scales - Indian lac insect -source of shellac; others sources of pigments.

Kermesidae — Gall-like coccids - on twigs and leave of oaks in US. Tamarisk manna scale, Trabutina mannipara, on Tamarix, female produce large amount of honeydew, in arid regions it solidiﬁes and accumulates in thick layers; sweet.

Dactylopiidae — Cochineal insects - female red in color, occur on cactuses; source of crimson dye; female collected and dried, and pigments extracted.