Biology, images, analysis, design...
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Identification & Distribution:Apterae of Cinara laricis are dark greyish-brown to reddish brown, usually with a wax bloom. Abdominal tergites II - VI are speckled with numerous dark sclerites dorsally and the hairs arising from them are conspicuous (thick and spine-like with raised conical bases).
The first picture above shows the numerous dark sclerites on the dorsum of an adult aptera on a larch twig. The second picture above shows an alate Cinara laricis along with some immatures.
The characteristic numerous irregularly-sized dark sclerites on the dorsum of the adult aptera are more clearly shown in the micrograph of Cinara laricis in alcohol above. They are not quite so prominent on the alate (above right). The siphuncular cones are blackish and conspicuous, but the pigmented radius may barely exceed the diameter of the opening. The body length is 3.0-5.1 mm.The ovipara (egg laying female) is similar to the viviparous female and has no pericaudal wax ring. The alate male of Cinara laricis is dark brown with a variable sclerotic pattern.
Cinara laricis aphids are found in small dense colonies on the twigs of the lower branches, or on trunks of young larch trees (Larix spp). The oviparae and alate males occur in October-November. This is one of two common species of Cinara found on larch - the other is Cinara cuneomaculata. The speckled larch aphid is found throughout Europe, and is also recorded from the Far East (Mongolia, China, Korea and Japan).
Biology & Ecology:
Cinara laricis colonies seem to start up somewhat later than most Cinara species, presumably because larch is deciduous and nutrients are not available so early in the year.
The aptera shown in the first picture above has matured in August and is now reproducing. Some of the nymphs are shown in the second picture varying in colour from grey to brown. This species produces copious honeydew, and is considered by Binazzi & Scheurer (2009) to be an optional myrmecophile. We have found it is usually attended by ants.
This southern wood ant has collected a large droplet of honeydew from one of the Cinara laricis. Rather than consuming it all itself, it will most likely share the droplet with other ants from the same nest, a behaviour known as trophallaxis.
Here Cinara laricis is being attended by southern wood ants (Formica rufa). Working in Russia, Novgodorova (2005) found that the speckled larch aphid was tended by four Formica species and by Lasius fuliginosus, but not by other Lasius or Myrmica species. The Formica species did not predate any of the tended aphids, even though they consumed large numbers of other aphid species such as Euceraphis. Lasius fuliginosus, on the other hand, did take some tended species, including Cinara laricis, after they decreased in the attractiveness as sources of honeydew late in the season.
This was taken in late October, when one would expect sexual forms to be present. The aphids shown here with (large) developing wingbuds may be developing males, or possibly brachypterous female oviparae. Note that there is also an apterous Cinara cuneomaculata in the picture top right.
Damage and controlHe & Yong-mu (1983) reported that Cinara laricis caused serious damage to Dahurian Larch (Larix daharica) used for urban greening along with three other aphid species. The cause for higher infestation on city trees than in natural forests was believed to be increased light levels and reduced abundance of natural enemies. Integrated control was proposed for the problem with only limited use of insecticide.