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A
biologcial key is a tool used to aid in the identification of an object,
eg. plant, insect. It is made up of a series of statements in groups of
two (dichotomous key) or more. After reading all the statements at the level
you are in, you move to the next level by choosing the statment which best
describes your object.
You
move throught the key by making choices at each level. The first choices
are usually broad characteristics and become narrower as you move along.
Finally, only a single choice remains. This will be the name of the object
you are trying to identify, as long as the object is included in the key
and no wrong choices have been made along the way.
Consider
a key like a road with forks in it. If you come to a final choice that
seems hightly unlikely, then back up to a level where you are very sure
of your choice and take the other pathway.
In
this key, you will be identifying which insect or mite has caused damage
to leaves of trees and/or shrubs.
|
Brief
Key to Common Damage to Leaves of Trees and Shrubs by Insects
and Mites in Manitoba
|
| Leaf
tissue becomes brown and papery ..... |
|
|
1 |
Leaf
tissue between upper and lower surfaces eaten. In some cases,
the two layers may be peeled apart .....
|
...leaf
miners |
| |
1 |
Upper
or lower leaf surface is eaten. Occasionally entire leaf tissue
is consumed, leaving only veins ..... |
...skeletonizers |
| Leaf
rolled or stuck together ..... |
|
| Leaf
or blossom chewed ..... |
...2
|
| |
2 |
Holes
or irregular areas in the leaves of deciduous plants - insect
a larva of a moth or butterfly - loopers and caterpillars ..... |
|
|
3 |
Small
green caterpillar hanging from threads on may deciduous trees
..... |
...cankerworms |
|
3 |
Small
to large blue-black caterpillar with spots on back, can cluster
in groups ..... |
...forest
tent caterpillar |
| |
2 |
Needles
of conifers eaten or partly eaten ..... |
|
|
4 |
Young
needles eaten first, then older needles. Larva has reddish brown
head, shiny yellow-green body, two dark green or brown stripes,
adult is a wasp ..... |
|
|
4 |
Young
needles of spruce and fir eaten at the base, rest of needle
entangled in a network of silk ..... |
...spruce
budworm |
| Leaves
curled up or wilted, may be sticky; groups of soft-bodied green
to black insects found. If wings are present they are held roof-like
over the body ..... |
|
| Leaves
spotted ..... |
...5
|
|
5 |
Pale
spots and blotches on green ash leaves, fast moving green to
black insects found. If wings are present, they are folded over
the body, appear somewhat hard and have a tringle marking on
them ..... |
|
|
5 |
Mottled
appearance on bur oak leaves, small flat bug with lacy wings
..... |
...
oak lace bug |
|
5 |
Leaves
appear stippled, bleached and brown; a fine silk webbing appears
around needles or leaf blaces; microscopic mites appear as dots
on white paper when branches are tapped ..... |
...
spider mites |
|
5 |
Conifer
needles have white spots ..... |
...6 |
| Bumps
and other distorted outgrowth found on leaves ..... |
|
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