Xanthogaleruca luteola (Müller, 1766) - Elm leaf beetle - Cyprus

Family: Chrysomelidae
Subfamily: Galerucinae
Tribe: Galerucini

Xanthogaleruca luteola, commonly known as the elm-leaf beetle, is an invasive beetle pest species in the family Chrysomelidae. The adul is 6–8 mm in length, ranges from yellow to green in colour, with a spot on its head, an hourglass mark and two spots on the pronotum, and a broad, dark stripe along the edge of each elytron. The larvae are usually black, occasionally black and yellow, with multiple rows of dots on the back and on the sides and < 13 mm long. The pupae are orange-yellow with black chaetae. The ova are yellow, and laid in spindle-like clusters of < 25 on the undersides of the elm leaves.

Distribution
These beetles are common in the Western Palaearctic ecozone from Portugal to Central Asia. Indigenous to Europe, it was accidentally introduced to North America and Australia. It is now widespread, and a serious pest in Australia and parts of North America.

Ecology
Xanthogaleruca luteola is a serious pest of the elm. Both the imagines and larvae feed on the emergent leaves of the elm. Repeated heavy infestation rarely kills the tree outright. It usually weakens it by defoliating it, rendering it vulnerable to disease. Falling branches usually allow for bark beetles to spread, which causes the Dutch elm disease. Elm leaf beetles do not transmit the disease. The beetles are active in the spring since elm leaf beetles cannot thrive in temperatures below 52 °F. In fact, weather is one of the most limiting factors in the population growth of Xanthogaleruca luteola. A late spring freeze or long winter can kill off entire elm leaf beetle colonies.

The imagines depart their hibernation sites (often houses) in early spring, the females laying their ova on the underside of the elm leaves. The ova hatch after one week, the larvae immediately feed on the underside of the leaves. This larval stage lasts for a period of between two and three weeks, at the end of which it will migrate to the lower part of the tree in search of bark crevices in which to pupate. The next generation emerges in mid-summer after two to three weeks' pupation, and begins feeding on the leaves. The female can lay < 800 ova, but this ovipositing may be interrupted by shortening of the photoperiod to < 14 hours, inducing a brief feeding bout before the search for a hibernation site.

Hosts include English Elm (Ulmus procera), Scotch Elm (Ulmus glabra), American Elm (Ulmus americana), Siberian Elm (Ulmus pumila), Chinese Elm (Ulmus parvifolia) as well as complex hybrids such as 'Homestead'. The beetle has also been reported on Zelkova serrata. From Wikipedia, the free encyclopedia.

Photos at Athalassa 11/04/2016, by Michael Hadjiconstantis.