88 Farmers’ Bulletin 1169. 
ELM LEAF-BEETLE.” 
How injurious.—The elm leaf-beetle (fig. 21,6) feeds on all species 
of elm, but the common English elm is its favorite. Wherever it is 
established and abundant it may, under favorable conditions, keep 
the elms in a constant state of partial or complete defoliation and 
eventually lead to their death. Hundreds of elm trees of all ages are 
known to have died as a result of continuous defoliation by it and 
subsequent attack by bark-boring insects. 
Evidence of infestation—From the time the buds burst in the 
spring until the leaves are fairly grown the leaves show irregular holes 
made by the beetles. Later in the season more of the injured leaves 
are skeletonized from below (fig. 21, a) by yellowish black to blackish 
yellow larvee (fig. 21, d, ¢, #) up to half an inch in length, which may 
also be observed crawling along the trunk. Clusters of 5 to 20 or 
more orange-yellow, elongate-oval, tapering eggs standing on end 
(fig. 21, ¢) in two or three irregular rows occur on the underside of 
leaves, and naked orange-colored pupex (fig. 21, 7) in crevices and 
under scales on the bark and on the ground at the base of trees. 
Seasonal history and habits —The winter is passed in the adult or 
beetle condition in any suitable shelter. When the buds begin to 
swell in the spring the beetles issue from their winter quarters, mate, 
and feed upon the leaflets. When the leaves are fairly well grown 
the females begin their egg jaying. In about a week the eggs hatch 
into larve, which begin to feed at once. Larve reach full growth 
in 15 to 20 days and transform to pup, which, 6 to 10 days later, 
change to beetles. In Washington two generations are produced 
annually, the eggs of the second generation appearing in July. 
Control—Whenever there is evidence that the insect is present in 
large numbers, spray the trees with lead arsenate (p. 11) just after 
the buds have burst and again two weeks later. Aim to spray the 
underside of the leaves. Rains soon after spraying may necessi- 
tate third and fourth applications of the poison to keep the trees 
fresh and green. Destroying the pupe at the base of trees by dig- 
ging up and exposing to weathering or by pouring hot water or thick 
soapsuds over them will assist in keeping the beetle down. 
Simultaneous community action, by individuals cooperatively or 
by the local government, is indispensable in the work of combating 
this insect, because unless all trees in a community are treated at the 
same time the results will be unsatisfactory. Cooperative action is 
advisable because elm trees are usually large and require costly spray- 
ing apparatus. Treatment of individual private trees by the com- 
munity outfit should be arranged for, in order that no trees may be 
left untreated. 
7 Galerucella luteola Miill. 
