Cbe national nurseryman 
FOR GROWERS AND DEALERS IN NURSERY STOCK 
Copyrighted 1909 by the National Nurseryman Publishing Co., Incorporated. 
' Vol. XVIII. ROCHESTER, N. Y., MARCH, 19ro No. 3 ’ 
THE CAMPAIGN AGAINST ENEMIES OF THE NURSERY 
AND ORCHARDS 
Spraying is at once a type of investment and an insurance. It is a direct investment in which the returns are 
much larger than the expenditure- It is an insurance all the time. The underlying principle is pre¬ 
vention. Success comes to the forehanded man. The best information available on the latest phases 
of spraying is to be found in this issue._ 
THE LESSER APPLE LEAF-FOLDER 
By R. L. Webster 
Recent Injury to Nursery Stock in Iowa. —During past 
years several Iowa nurseries which grow large quantities of 
apple stock have been seriously troubled 
by a small green caterpillar which folds 
or ties up the young tender leaves of the 
growing trees, stunting the growth of the 
stock. This small caterpillar is known 
as the “lesser apple leaf-folder,” on ac¬ 
count of its habit of folding apple leaves. 
Plum stock also is attacked, as well as 
apple stock. The scientific name of this 
‘ pest is Peronea minuta. 
In 1908, the Entomological section of 
! the Iowa Experiment station took up the 
study of this insect and made some 
spraying experiments to determine how 
j , it might best be controlled. The result 
of this work has thrown considerable light 
on the habits of this leaf-folder in the 
nursery and definite information can 
now be given for the critical times to 
spray for the pest. 
Appearance of the Injury. —Apple stock 
of all ages is attacked by the leaf-folder, 
1 the young grafts as well as the 3-year-old 
trees. The new leaves on the terminal 
( branches of the trees are favorite posi¬ 
tions for the leaf-folder to work. The “worm” or larva, 
folds a single leaf, or ties several small leaves together, and 
remains inside this hiding place, where it- feeds undisturbed. 
As a result, infested trees present a tied-up and scraggly 
appearance where, the leaf-folders become very numerous. 
The leaves within which the folder works turn brown as a 
result of the feeding, and a badly infested block of apple 
stock may have the appearance of having been swept by fire. 
Specific Indications of the Presence of Leaf-folder. —As its 
name indicates, this insect folds the leaves of the apple. A 
small tender leaf may be folded longitudinally along the 
midrib, with the upper surface drawn over, and the whole 
leaf presenting a flat appearance. Where a young larva 
folds a comparatively large leaf only a part of the margin is 
* folded over the upper surface and fastened down flat to the 
leaf. Frequently several young larvae will tie up the tender 
unfolding leaves of the growing tips and work inside the 
protection thus formed. In such a place 
the larvae often bore through the tender 
leaves, riddling them with small holes. 
Again, where two large leaves are con¬ 
tiguous the larva may sew them flat 
together, and live in the hiding place 
formed between the two. 
In June and again in August, in Iowa, 
the orange-colored moth of the leaf-folder 
may be seen flying about in the rows of 
nursery stock. The time when these 
moths are flying in any numbers is an 
important one, since this marks the 
proper time to spray for the second and 
third broods of the leaf-folders. If the 
third brood is very numerous the slate- 
colored moths may be seen among the 
leaves in the nursery row in October. 
The Insect's Appearance. —The leaf- 
folder itself is a greenish yellow “worm,” 
about half an inch long when it is full 
grown. It is slightly hairy, but these 
hairs, or setae, are hardly noticeable. 
When the leaf-folder has reached its full 
growth it changes to the pupa, or resting 
stage, during which it is quite inactive and does not feed. 
This pupa is about three-tenths of an inch long, brown, with 
a small knob in front of the head. After a week or ten days 
in the summer the moth, or adult insect, emerges from the 
pupa. These moths deposit their eggs, usually on the 
leaves, from which eggs hatch a new brood of young leaf- 
folders. 
There are two different forms of the moths, an orange 
colored form, (Fig. 4). which appears in the late spring and 
in the summer; and a slate-colored form, which appears in 
the fall. Thus for the first and second brood the orange 
moth appears, and for the third brood, the slate moth, both 
being the same species of insect. Such a phenomenon is 
known as dimorphism, that is, having two forms. Both the 
orange and the slate forms measure about a third of an inch 
Fig. 1. Work of Apple Leaf-Folder. Reduced. 
