Insects of Shade Trees and Their Control. 49 
number of caterpillars present, but when abundant these are known 
to defoliate entire branches and trees. In our prairie regions, where 
trees are so scarce and precious, the injury to willows and poplars 
is most serious. 
Appearance and habits—If parts of leaves are missing or entire 
branches or trees are bare and stocked with black, red-marked, spiny 
caterpillars (fig. 29, 9), about 2 inches long, feeding in groups, it is 
safe to conclude that this insect is the one responsible for the damage. 
On maturing the caterpillars change to strange looking sea-shell 
shaped chrysalids (fig. 29, 70) which may be found suspended from a 
limb and fastened to it by the small end. After a few weeks the beau- 
tiful butterfly, known as the “mourning cloak” (fig. 29, 77), the first 
butterfly to appear in the open in early spring, issues and, after 
mating, lays a batch of from 300 to 400 eggs (fig. 29, 7, 8) in a ring 
about the twig of the food plant. From one to three generations are 
00a, 
Fie. 30.—A hackberry butterfly, Chlorippe celtis: a, Eggs; }, larva, dorsal view; 
ce, d, chrysalis, dorsal and lateral views; ec, imago, male, dottcd line showing form 
of female. (Riley.) 
produced annually. The insect overwinters in the adult stage, the 
butterflies hiding under rocks and bark scales for protection. 
Remedies.—Spray with lead arsenate (p. 11) as soon as signs of 
injury are observed. In some cases the twigs with clustered cater- 
pillars may be cut off and the caterpillars destroyed by crushing, 
burning, or dipping in kerosene. 
HACKBERRY BUTTERFLIES.” 
How injurious—The caterpillars of these butterflies feed on hack- 
berry leaves wherever these trees grow and often greatly mar their 
appearance. As the hackberry is extensively grown as a shade tree 
* Chlorippe celtis Bdy. and C. clyton Bdv. 
5692°—20—-4 
