Psylliodes attenuata (Koch, J.D.W., 1803)

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POLYPHAGA Emery, 1886

CHRYSOMELOIDEA Latreille, 1802

CHRYSOMELIDAE Latreille, 1802

ALTICINAE Newman, 1834

Psylliodes Latreille, 1829

This species occurs throughout the Palaearctic region from Europe to the far east of Russia, China and Japan, it extends south across the Middle East and Asia Minor and is generally common and often abundant throughout, sometimes occurring in huge numbers and becoming a serious economic pest of various crops, it is common across southern and central Europe but more local and scarce further north to the UK and southern provinces of Sweden and Finland. It was formerly widespread and locally common across the south of England and recorded as far north as Scotland but suffered a drastic decline during the twentieth century, probably due to reduced commercial hop cultivation, it is now known from only a very few scattered locations in Kent, Nottinghamshire, Warwickshire and North Wales and is considered to be endangered. Host plants include various Cannabaceae; wild and cultivated hops (Humulus lupulus L.) and hemp (Cannabis sativa L.) and adults also feed on nettle (Urtica dioica L.) foliage. Adults are more injurious to plants than larvae; they produce small holes in tender stems and foliage but when present in numbers whole plants can become skeletonised, they may destroy small seedlings in the spring and cause extensive damage in late summer and autumn when the new generation emerges. Adults overwinter in the soil and can survive severe and extended frosts, they emerge during March and April and begin feeding, if the usual hosts have not sprouted they will feed for a while on other herbaceous foliage, usually nettle but also a range of other plants, mating occurs soon afterwards and most of these adults will survive into June or July. At this time they are particularly dangerous as low temperatures send them to the soil surface where they consume cotyledons and developing stems. Females oviposit in soil around host stems; each will produce about 300 eggs and lay them at a depth of about 8 cm, away from surface predators. Larvae emerge from one to three weeks later, depending on soil conditions, and begin feeding on tender lateral roots, working their way to the main root where they produce long feeding galleries and sometimes attack the lower stems but this damage rarely kills the plants, they pass through three instars and are fully-developed within three to seven weeks. Mature larvae leave the roots and construct earthen cells in which they pupate and adults eclose between one and five weeks later. Through late summer these adults feed on apical leaves and seeds of the host plants and may cause extensive damage before they enter the soil to overwinter. Adults may be sampled by sweeping but they hop readily and fly well and so are easily missed.

Psylliodes attenuata

Psylliodes attenuata

© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm

2.0-2.8 mm. Elongate-oval with broadly rounded shoulders and long elytra, body metallic green or bronze, usually with the elytral apices reddish, antennae pale with darkened apices, legs extensively pale with the hind femora and bases of the fore and middle femora black or dark grey. Head clearly visible from above in normal setting, with a distinct X-shaped impression between the eyes but otherwise smoothly convex and finely punctured. Pronotum broadest at the base and narrowed to long, protruding margins behind distinct anterior angles, surface smoothly con vex and with a mixture of very fine and moderately strong punctures throughout. Elytra with rounded sloping shoulders, without humeral calli, striae strongly punctured from the base and becoming weaker towards the apices, interstices finely punctured. Hind femora greatly expanded, hind tibiae only weakly curved and with a series of three to six fine teeth along the external margins.

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