Tetraneura ulmi · guobinis gumbadaris amaras «Tetraneura ulmi · guobinis gumbadaris amaras^Thumbnails»Tetraneura ulmi · guobinis gumbadaris amaras«Tetraneura ulmi · guobinis gumbadaris amaras^Thumbnails»Tetraneura ulmi · guobinis gumbadaris amaras«Tetraneura ulmi · guobinis gumbadaris amaras^Thumbnails»Tetraneura ulmi · guobinis gumbadaris amaras

Tetraneura ulmi · guobinis gumbadaris amaras

  • elm sack gall aphid, elm-grass root aphid, fig gall
  • Elmegallebladlus, Elmegallelus
  • Ulmenblasenlaus
  • guobinis gumbadaris amaras
  • vīksnu-labības laputs
  • Iep-grasluis
  • torebnica wiązowa, bawełnica wiązowo-zbożowa
  • almgallus, almpunglus

Kiti augalų gãlai

It is found in Asia, Europe and North America, causing abnormal plant growths, known as galls on their primary host, elm trees (Ulmus sp.). The gall is a stalked, club-like smooth pouch (7−15 mm high) on the leaves of elm trees. Feeding inside the gall is a nymph and some wax. Partly formed galls are pale yellow patches with irregular lumpy projections on the top surface of the leaf. On the underside of the leaf, young galls may have a hairy opening.

Mature asexual females leave the galls in the summer and lay eggs on grass roots. The aphids are pink, orange or purple, 2–3 mm long and covered in a thin layer of powdered wax. In the autumn, winged forms fly to elms and give birth to wingless mites of both sexes. After mating each female lays an egg and a female nymph hatches in the spring and starts feeding on the underside of a leaf. The leaf reacts by forming a tiny, yellowish pimple on the upper side, which is the early growth of a gall, into which the nymph enters, feeds and produce offspring.

Most of the text below is from influentialpoints.com/Gallery/Tetraneura_ulmi_Elm-grass_root_aphid.htm, where it was published under a CC BY 3.0 License.

On the primary host, elm, Tetraneura ulmi develop within galls on the leaves. The galls (see first picture below) are stalked, approximately bean-shaped, smooth and shiny, and coloured reddish-green and/or yellow. The Tetraneura ulmi fundatrix (see second picture below), which induces production of the gall, is light green with the head, thorax, antennae and legs dark and transverse bands of light wax across the abdomen and thorax.

The offspring of the Tetraneura ulmi fundatrix develop within their gall to winged viviparous alates (see first picture below) which have a shiny black head, thorax, antennae and legs, and greyish black abdominal segments. The body length of Tetraneura ulmi alates is 1.8-2.6 mm. The adult apterae on the secondary host, grass roots (see second picture below), are readily identified, being pale orange yellow, yellowish white or reddish. The head, prothorax and appendages are brown, and the body is (sometimes) lightly dusted with wax. Tetraneura ulmi has small conical siphunculi, with a flange (cf. Geoica utricularia which has no siphunculi).

Tetraneura ulmi host alternates. The winged forms of the elm-grass root aphid (known in America as the elm sack gall aphid) emerge from elm galls (Ulmus spp.) in June-July to colonize roots of grasses (Poaceae). Populations without sexual forms occur commonly on secondary hosts. In September winged forms make a return migration to elm where they produce larvae which feed on the bark, and mature to apterous males and females. Fertilized females only lay one egg each. Tetraneura ulmi is found in Europe, across Asia to eastern Siberia, and has been introduced to North America.

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