Practical Keys to the Orders and Families of Forest Insects, 
Based on Types of Injury 
The following keys are designed for the use of those unfamiliar 
with the orders, families, and genera of insects. The insects are 
first separated into primary divisions according to the portions 
of trees attacked, the size of the trees, and the timber products 
infested. These main divisions are in turn subdivided to other 
groups or subdivisions. 
PRIMARY DIVISIONS OF KEY 
Te Insects injurious to seeds, seedlings, young plantations, and 
small reproduction. 
A. To seeds, cones, and fruits. 
B. To seedlings and small reproduction. 
II. Insects injurious to large reproduction, forest trees, and 
shade trees. 
A. Acarina (red spiders). 
B. Defoliators, leaf miners, etc. 
C. Twig and tip damage, etc. 
D. Borers in wood and bark. 
E. Galls, swellings, etc. 
F. Sucking Insects. 
III. Insects injurious to forest products. 
A. Defects in green timber. 
B. Insects in round logs. 
C. Insects in lumber. 
D. Insects in material in ground. 
E. Defects in wood in salt and brackish water—marine 
borers. 
DIVISION I 
INSECTS INJURIOUS TO SEEDS, SEEDLINGS, YOUNG PLANTATIONS, 
AND SMALL REPRODUCTION 
This group includes the insects that attack the fruit and seeds 
of forest trees, also young seedlings in the nursery, plantation, or 
forest. Insects attacking seedlings more than 4 or 5 years old and 
somewhat shrubby and woody are discussed under Division II. 
A. Insects Attacking Seeds, Cones, and Fruits 
1. Larvae without well-developed head capsule; maggot-like: 
With a sclerotized structure like a breastbone near an- 
terior end; in seeds of fir, cypress, birch, and fruit of 
chokecherry Diptera, Cecidomyiidae 
Without breastbone; mouth parts well developed; in 
fruits of cherry, apple, plum, hawthorn; in berries of 
dogwood, holly, and others; and in walnut husks 
Diptera, Tephritidae 
Larvae with distinct head capsule . 2 
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