Tree lice

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Tree lice
Tree lice of the genus Cinara

Tree lice of the genus Cinara

Systematics
Class : Insects (Insecta)
Order : Schnabelkerfe (Hemiptera)
Subordination : Plant lice (Sternorrhyncha)
Superfamily : Aphids (Aphidoidea)
Family : Tree lice
Scientific name
Lachnidae
Herrich-Schäffer in Koch , 1857

The lachninae (Lachnidae), also cattle lice or Lachniden called, are a family of plant lice (Sternorrhyncha) and belong to the superfamily of aphids (Aphidoidea) to. Most members of this family are considered to be forest pests, but some species are very important for beekeeping as producers of honeydew , the raw material of forest honey .

features

The characteristics of the tree lice correspond to the general characteristics of the aphids . There are colourations and color patterns in the range green, light gray to black and brown. Some species secrete white wax threads.

Way of life

Tree lice feed on phytophagus by sucking sap from their host plants. They are found on annual or perennial shoots, e.g. B. on the young conifer shoots (May shoots), but also on the already lignified areas of the conifers . They pierce the pathways ( phloem ) of the tree and thereby excrete the excess amounts of carbohydrates in the form of honeydew . This also creates melezitose , a triple sugar that acts as an attractant for ants.

The winged animals are often transported far by the wind and can thus colonize areas further away. The wingless shapes are sluggish and move slowly. You can't hop and jump either.

development

The tree lice develop during the vegetation period in a predetermined generation sequence, depending on the species, with sexual reproduction and oviposition as well as virgin generation ( parthenogenesis ) and live birth. Both winged and wingless forms occur. The former are used for spreading and changing hosts , the others for mass reproduction. With a few exceptions, tree lice are monoecious , i. that is, they live exclusively on one type of host plant. The generation sequence begins with eggs laid in autumn, the larvae of which hatch early in spring after overwintering.

The reproductive rate of tree lice varies greatly depending on the species. B. in the Cinara pilicornis quite high and in the Cinara pectinatae relatively low.

Benefits and harmful effects

Some species can cause great damage to their host trees. So z. B. the mass reproduction of Cinara pini on young pines to growth disorders.

Other species, on the other hand, only lead to relatively harmless soot dew formation due to the secreting of sugary honeydew , but with a correspondingly strong mass increase, which depends on many factors and does not occur every year, to very good yields of forest honey . For this purpose, the beekeepers population development of lice observed. In some cases, so-called forest costume observation groups have also formed for this purpose. In addition, individual bee colonies in the forest are placed on scales at different locations that appear suitable (so-called weighing colonies). If there is a corresponding increase in weight, then it is hiked, i.e. that is, greater numbers of colonies of bees are brought there. During this time, the beekeeping associations also set up appropriate telephone costume reporting services in order to announce the corresponding results for individual areas.

Naming and systematics

Neither the naming nor the classification ( taxonomy ) is uniform for the plant lice . When it comes to naming, the German term tree lice is found in the field of biology , whereas the name bark lice has been used in beekeeping literature for decades .

Genera and species (selection)

A colony of the Great Black Spruce Louse on the trunk of a spruce

Sources and references

  1. ↑ Insects - a small reference work - U. Ord. Aphidina ( Memento from June 20, 2008 in the Internet Archive )

literature

  • Gerhard Liebig: The forest costume - origin - observation - prognosis. Self-published in Stuttgart 1999.

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