Corythucha ciliata

The adult sycamore lace bug is milky white in colour and between 3.2 and 3.7 mm (0.13 and 0.15 in) in length. It is similar in appearance to the cotton lace bug (Corythucha gossypii) and the Florida oak lace bug (Corythucha floridana), but lacks the brown crescent-shaped band on the carina (ridge on the body-wall) of the former and is larger than the latter. The only brown colour is a small spot on the protuberance on each elytron (wing-case).[5] The nymphs are oval in shape, dorso-ventrally flattened, black and prickly.[6] This lace bug can most easily be distinguished from other species by its presence on sycamore.[5]

C. ciliata is native to North America and is found where its host trees grow. The main host is the American sycamore (Platanus occidentalis) but it is sometimes found on other species of Platanus, and it has been recorded on Broussonetia papyrifera, Carya ovata, Chamaedaphne sp., Fraxinus sp., Quercus laurifolia and Liquidambar styraciflua.[5]

In Europe, C. ciliata was first observed in 1964 in Padova, Italy, and has since spread throughout Southern and Central Europe, infesting the European hybrid plane (Platanus × acerifolia).[7][6] Although it does not by itself kill trees, in Central Europe it is often found in association with two plant-pathogenic fungi which can kill trees, Apiognomonia veneta and Ceratocystis fimbriata, leading to the hypothesis that it may act as a vector for these fungi.[5]

Lateral view

After the adults have mated, the female lays eggs on the undersides of leaves of the host tree, usually near a fork in the veins. When the eggs hatch, the juveniles stay close together at first, only moving onto a new leaf at the fourth instar stage. They puncture the epidermis of the leaf with their mouth parts and suck sap. There are five instars, after which the nymphs undergo incomplete metamorphosis to become adults. During the summer in Oklahoma, the whole cycle takes about 44 days. In the warmer parts of the insect's range, there may be several generations each year.[5] The insects are restricted to the underside of the leaves where little black mounds of dried frass can be seen and the shed skins of the nymphs often adhere to the leaf. The upper surface of the leaf is speckled with white, near the veins at first, and the leaf becomes progressively paler or bronzed and may fall early. Overwintering generally takes place as adults in crevices or under flakes of bark, the insects being able to withstand temperatures down to at least −24 °C (−11 °F).[6]

Wikimedia Commons has media related to Corythucha ciliata.

• Corythucha ciliata in CABI's Invasive Species Compendium