274 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
trees have been successfully sprayed with lead arsenate at Bogalusa, 
La. Snyder (393), however. did not consider the cost justifiable, eX- 
cept for ees reasons. 
The adult of the imported willow leaf beetle (Plagiodera versi- 
colora (Laich.) ) isa small, moderately stout, metallic-blue or greenish- 
blue beetle, about 3 mm. long, closely resembling some of the common 
flea beetles in appearance. The ventral surface, the legs, and the an- 
tennae are also blue, although the latter at times appear to have a 
reddish-brown sheen. The eggs are yellow. The head and legs of 
the larvae are black, and the “body bears numerous black and brown 
markings. When full-grown, the larvae are about 5 mm. long. The 
pupae are straw- colored at first, darkening later, and are about the 
same size as the adult. 
This beetle, which is a pest of ornamental trees, is of European 
origin. It was first reported in the United States from Staten Island 
im 1915, although records indicate its presence there since 1911. It is 
now common throughout New England and has been collected as far 
west as Little Falls, N. Y., and as far south as Virginia. Both smooth 
and glossy-leaved willows are severely attacked. The black willow 
(Salix nigra Marshall) and the shiny willow (S. ducida Meuhl.) are 
very susceptible, whereas some species, such as the weeping willow 
(S. babylonica L.) and the sandbar willow (S. longifolia Meuhl.), do 
not appear to be favored. Lombardy poplar (Populus nigra vay. 
italica Du Roi) has also been recorded as fed upon by this beetle. 
The winter is passed as an adult under bark and in other sheltered 
places. Activity is resumed about the time the fohage appears, and 
the beetles feed for a time by cutting holes in the leaves. The eggs of 
the first generation are laid from late April to June, depending on the 
weather and the locality. They hatch in about a week, and the larvae 
skeletonize the leaves, feeding on both the upper and lower surfaces, 
although more commonly on ‘the latter. Pupation takes place on the 
leaves, and at times, according to Dowden (/37), a high percentage 
of the pupae are destroyed by a parasite, Schizonotus sieboldi Ratz. 
In southern New England and New Ye ork there are at least two com- 
plete generations; in some localities in that region and in Virginia, 
there may be three and a partial fourth. 
Closely related and very common on willows, poplars, and alders, 
wherever they grow in the eastern part of the United States, as well as 
farther west, are the cottonwood leaf beetle (Chrysomela scripta 
F.), and two European species (. interrupta F. and C. tremulae (F.). 
Both adults and larvae feed on the foliage and at times chew the 
tender bark at the tips of the twigs. Severe infestations are not com- 
mon, but when they occur, considerable damage is done. When the 
culture of basket willow flourished about 35 years ago in some parts 
of western New York, these insects were Important pests. 
The adults of C. seripta and C. interrupta measure from 5 to 8 mm. 
in length. There is a great variation in the coloration of both species. 
In (. scripta the head and thorax are black, with marginal markings 
or dark yellow or red on the latter. The elytra will vary in color from 
almost pure golden to almost black, but most often they are yellowish 
with black interrupted stripes. In C. interrupta the head and thorax 
are similar to (. scripta, but the elytra are a deep yellow or red, vari- 
ously spotted with black marks. The adults of C. tremulae are a little 
