The adult body is oval, 2.6-4 mm in length and deep-brown. It has short hairs on the front and sides of pronotum and along the edges of the elytra. Pronotum and head are nearly black. The elytra, the border of the front and back edges of pronotum, femur tops and shanks are ochre- or reddish-brown. Elytra of old specimens are deep-brown and hardly differ from the common body colour. The frontal part is covered with dense dots that merge together and form longitudinal (though some are skewed) scrobes. The areas between the scrobes are covered with small dots and grains. The wide pronotum which narrows from the middle to the front is characterised by almost parallel side edges in the back half and clear interception near the front edge. Its length is one sixth shorter than its width. Dots situated on the pronotum are clear, more or less dispersed, in the middle part they are lightly linear-oval. Spaces between dots are marked with small spots, which are hardly noticeable.
The wide elytra are evenly rounded on the top. The width of the elytra at the base amounts to about three fourth its length. The abdomen is prominent. The first- and second-segments of the abdomen are joined; however, the joint between them is barely visible (Stark, 1952).
S. morawitzi is widespread throughout the range of the Asian and East-European Larix spp. except in parts of far-eastern Russia (Magadan Region, Kamchatka and Sakhalin). It is also found in north-eastern regions of the European part of Russia.
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Larch infested with S. morawitzi can be identified by resin flowing from sites of attempted attack, the characteristic gallery system with a central maternal chamber and radiating larval galleries and sparse crowns with dead tops and branches.
S. morawitzi inhabits thinly stocked stands with large amounts of light. It is typically found in burnt-out forests and areas where there has been selective cutting. It is rare in undisturbed stands of average density.
S. morawitzi mainly invades the lower branches of healthy trees, as well as branches and stem tops of impaired trees; it will also attack both drying out and cut green wood.
The gallery system of S. morawitzi consists of a short (5-13 mm long) arc-wise curved maternal gallery and larval galleries (6-15 cm long by the time the larva has reached full development) which extend away from it. The number of larval galleries very seldom exceeds 20. But occasionally their number amounts to 30. Sometimes the galleries are weakly curved and stretch mainly along the branch or diverge in different directions, in other cases they have multiple curves and are tangled. The maternal galleries are quite often filled with a gum and as a result larvae do not develop there. The whole gallery system is situated on branches that rapidly die back.
The galleries leave prints on the sapwood; however, pupae cradles always scar the sapwood deeply and are usually in the longitudinal direction.
Sometimes on stems and thin branches larval galleries are fully situated in the bast while maternal galleries and pupae cradles only leave prints on the sapwood.
Most beetles fly from the middle of July to the middle of August.
Despite the maternal gallery of S. morawitzi being very short, the female doesn't lay her eggs at once but instead lays them during the process of making the gallery. Eggs are only laid on the side of the gallery that goes deep into the sapwood. Males do not enter the maternal galleries. Throughout the full period of adult emergence they are found on the bark surface of invaded trees. According to Florov (1949), Isaev and Utkin (1963) during oviposition which lasts 8-12 days the female copulates two or three times. In many cases, females leave the maternal gallery as soon as oviposition has finished; other times they die directly in the gallery.
Mass larvae emergence takes place in the middle or third week of June. Larvae feed and achieve most of their size by the first Autumn frost, then go into hibernation. Most of the larvae will feed again briefly in the spring and start to pupate at the beginning of June. However, some pupate around the beginning of August. The developmental cycle takes one year.
The emergence of the first young beetles from hibernation takes place in the middle of June. At the end of the month their number exceeds the number of larvae and pupae. During the whole of July eggs, young larvae (in gallery systems of the new generation), larvae of the older generation, pupae and young beetles are found in the galleries of S. morawitzi.
According to Isaev and Utkin (1963) the additional feeding required by adults of S. morawitzi takes place in isolated curved galleries (0.7-1.3 cm long) or round enlarged cavities. These galleries are characterised by the absence of boring dust in them. They are most often situated in the thick bark of the stem and on branches. After making the emergence gallery some individuals return to the place of development and begin additional feeding by gnawing the sides of the pupae cradles.
S. morawitzi is an important pest in larch stands, though its actual economic impact is usually minor. S. morawitzi does not invade the stems of viable trees, but will invade impaired branches and tops. S. morawitzi can only develop on dying trees that are unable to exude protective gum.
The damage caused by S. morawitzi precipitate the process of senescence, whether it is the dieback of lower branches of sound trees, or the death of trees damaged by fire, or trees already impaired as a result of invasion by other stem pests.
However, there are other opinions concerning the damage caused by S. morawitzi; according to Kazachinskaya and Kondakov (1964) it belongs to a group of insects that cause severe damage of Larix sibirica in the Krasnoyarsk Region, Russia. According to Isaev and Utkin (1963) S. morawitzi is a serious pest of L. daurica in the Amur Region, Russia, where it causes extensive destruction on fire damaged sites. Here, it is dominant among the stem entomofauna.
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Control efforts focus on improving the resistance of forests and eliminating infested trees, as well as the use of chemical and biological preparations.
Control efforts should be undertaken in the area of the present distribution of Scolytus morawitzi. Control measures include forestry and sanitary measures (improving of the resistance of forests, cutting and elimination of all infested trees; cutting of "trapping trees" followed by their treatment), as well as treatments with chemical and biological preparations.
Entomophages may play an important role in the regulation of the pest population, but there is no experience of using them for bilogical contol.
Isaev AS, Tarasova DA, 1963. Formirovanie ochagov stvolovych vreditelej v listvennichno-sosnovych lesach Srednego Priamuriya. Voprosy lesozashtity, t.2, MLTI, Moscow, 38-41 (in Russian).
Isaev AS, Utkin AI, 1964. Nizovye pozhary v listvenicznych lesach Vostocznoj Sibiri i znoczenie stvolovych vreditelej v poslepozharnom sostoyanii drevostoya. Zashtita lesov ot nasekomych-vreditelej. Moscow, AN SSSR, 118-189 (in Russian).