Synonyms and other taxonomic changes
Xanthogaleruca luteola (Müller)
Orig. Comb: Chrysomela luteola Müller, 1766
often listed as Pyrrhalta luteola, but this combination is not found in relevant European sources.
Explanation of Names
lute - Latin for 'yellowish' (1)
Base color yellow to olive green...darker in overwintering form (from couplet 17, page 13 of Wilcox(4)
Head with a dark occipital spot (behind and between the eyes) and typically a second black frontal spot (above antennae);
Pronotum with a dark central "hourglass" marking and two lateral spots;
On each elytron: a broad, dark stripe along the entire outer edge; and a much shorter, dark (sometimes vague) medial stripe at the base. Some (overwintering or teneral?) forms have elytra almost entirely dark.
adventive, now widespread in N. Amer., but most common in sw US (BG data)(5)(6)
Native to w. Palaearctic (7)
first detected in Baltimore, MD in the late 1830s (5)(6)
looks very similar to some species of the genus Trirhabda
, for which it is often mistaken.
The technical key character distinguishing them involves the relative lengths of the third and fourth antennal segments: in Xanthogaleruca
the 3rd antenna segment is longer
than (or subequal to) the 4th; whereas in Trirhabda
it is shorter. (See couplet 11, on pg. 12 of Wilcox(4)
However, sometimes the 3rd and 4th antennal segments appear nearly equal in length. In this case, other characters can often help separate Xanthogaleruca from Trirhabda.
At the base of each elytron in the typical form of X. luteola
there is a short, dark, medial spot or stripe (cf. Fig. 28, pg. 125 of Wilcox(4)
). But this may be obscured in forms with uniformly dark elytra.
In addition to the occipital spot present in both genera, X. luteola usually has a second "frontal" spot on the head, just above the antennae (which is almost always lacking in Trirhabda).
One last consideration...X. luteola is an introduced species from Europe and is usually found near parks or towns where its host, Elm trees, have been planted. All our species of Trirhabda are native to North America, and are usually found in less disturbed or wild areas.