Lamprodila festiva

Lamprodila festiva (synonym: Palmar festiva)

Profile

The juniper beetle is a metallic green colored beetle that is common on its main host plant, the juniper. Although the very splendidly colored beetle is considered rare and is therefore on the red list in Germany, an increasing number of damages have been registered recently. It is also responsible for a certain proportion of damage to other cypress plants, such as thuja.

Appearance

The metallic green shimmering jewel beetles are 6-12 mm long, streamlined and show steel blue spots on the neck shield and on the elytra.

The cream-colored larvae are 15-20 mm long, legless, and show strongly sclerotized mandibles at the anterior end. The anterior part of the thoracic segment is strongly broadened compared to the rest of the narrow body.

Biology

For oviposition, the beetles produce a short cut in the bark with their ovipositor and lay the eggs in the bast between the bark and the wood body. The feeding tunnels of the larvae are usually found on the sunny side of younger shoots and branches in the bast and superficially in the wood body. These, like the larvae themselves, have a flat oval cross-section and brown bore meal. When these tunnels completely encircle a branch, this cuts off the sap flow and the branch dies. After overwintering as a larva in deeper layers of wood, pupation occurs the next spring in a small cavity made vertically in the wood.

In early summer (around the time of the linden blossom), an adult jewel beetle hatches from this cavity, thus completing the cycle. Only one generation of beetles develops per year.

Damage symptoms

The juniper beetle causes a characteristic pattern of damage through the feeding tunnels of its larvae. In otherwise healthy looking thuja, individual branches die and turn brown. If the bark of such dead branches is cut superficially, the cause of the damage becomes visible. Between the bark and the body of the wood there are wide, shallow feeding tunnels, which are partly filled with feeding and excrement crumbs. These feeding tunnels cut off the sap flow to the twigs, and the green scale leaves dry out and turn brown. It is characteristic that only individual branches always turn brown and not the entire plant. After the beetles have hatched, the infested shoots show the typical transverse oval holes up to 5 mm in size.

Host plants

Juniper beetles live on various cypress plants of the genera Juniperus, Thuja, Cupressus, Chamaecyparis and Platycladus.

Distribution

The beetle originates from the Mediterranean region and has spread north and east in recent decades. Besides Austria, it is already found in Germany, the Czech Republic, Hungary and Slovakia, among other countries.

Propagation and transmission

It is believed that the spread of the juniper jewel beetle is favored by climate change and its spread is promoted by the increasing demand for cypress plants as ornamentals in gardens.

Economic importance

Due to the fact that the juniper spotted beetle can infest not only stressed but also healthy plants and cause them to die within two to three years, this beetle is definitely of economic importance and must be controlled regularly, especially in nurseries.

Prevention and control

  • As a preventive measure, ensure that the plants are well supplied with water and nutrients, as weakened plants are preferentially attacked.
  • Deeply cut out and destroy heavily infested plant parts (branches, twigs)
  • Treatment with chemical preparations does not seem to be useful
  • Judge from case to case whether measures are necessary at all: after all, this is a very beautiful, so far rare beetle

Last updated: 18.01.2022

automatically translated