8. Rearing the
Instructions for dissections of Phragmites
We will provide a basic data record sheet for
the dissections that you can download from this website. You can obviously
create your own but make sure that the essential information is recorded. Most
likely, students working with individual stems will make notes on pieces of
paper for each stem and then create a clean copy for record keeping. It is
important that all stems are individually numbered and that the quadrat for each
stem is known. That suggests that working with a single quadrat is the safest
approach preventing confusion. Number stems consecutively, even if moving to a
new quadrat. Have all materials for storage or rearing of insects ready before
beginning the dissections. Ideally, you can work in several teams on long lab
benches (Phragmites stems are very long) processing each stem separately.
- Open the first bundle and take a single shoot.
- Measure the length (in cm) and
diameter (in mm, using calipers) of the stem. The length of the stem is from the
base of where the shoot was cut to the flowers or shoot tip. Make sure to
stretch out the entire stem. The diameter is measured just above the lowest
internode that is available. Do not measure the internode because that will
inflate the stem diameter.
- Record whether the
plant has flowered or not
- Record whether the stem is broken
or not (if you folded the stem do not record this as broken)
- Note whether there is any bird
damage to the stem (large holes, such as from bird beaks, as opposed to small
holes which might be due to insects) (Provide picture).
Record whether side shoots have formed (Provide
- Dissect the stem with a pocketknife
starting at the bottom. Go slowly; do not slice through it completely in a way
that would injure the insects that might be living inside. Some species are
small and difficult to spot. Be careful not to overlook these or the ones in the
shoot tips. On plants that have not flowered often we find maggots living in the
picture These are called shoot tip flies. Carefully dissect the tip all
the way to the end. Occasionally the tips form a gall (hard tissue, larger
diameter than the stem) and the larva is found inside.
Record which species you find and where. Keep the
insects for rearing (see below) or as reference specimens in alcohol. If you
decide to take reference specimens, very often it is important to keep parts of
the stem where you found the insects as well. This will often help in
identifying the species. (for more details see the descriptions of the different
insect species below)
- If you find an insect, stop
- Create a simple drawing of the insect as
it looks in the stem or identify it using the picture guide provided later
(see common insects in Phragmites in North America section).
- When you see an insect that you or others
in your class have not seen before, share your finding with the class and
come up with a name that will be used for counting this insect during all
future dissections. For easier communication with other participants we have
provided common names for most species (see below) but for some they do not
exist. You may need to use the Latin names. This introduces the students to
the scientific concept of naming species.
- Notice any other organisms or structures
that might be present where the insects are present (such as fungi, galls,
- If you find an insect or a structure that
you are unable to identify using our materials (we expect surprises!),
please create a drawing, take a picture and try to rear the insect (most
often, only adults can be identified to species by a taxonomist. We often
send specimens to the Natural History Museum in Washington DC to help with
identification). Send information about your finding to Cornell University,
send a picture or the sample and we will help in identifying the organisms
Once all data about an insect have been recorded and the species is
identified (if possible), you can put the insect in a jar, petri-dish or
vial and wait for it to complete development. Adult insects usually emerge
within a few weeks after stems are brought into room temperature. This shows
students how morphologically different larvae and adult insects really are.
These adult insects can also be added to an existing insect collection at
the school (or starting one). This is a great opportunity to learn more
about insect life cycles and how different temperatures may influence the
speed of development.
If no insects are found in a particular stem,
or if you have completed recording findings on your data sheet, go back to step
one and dissect another stem. Insects will not be present in every stem.
- If no insects are found in a
particular stem, or if you have completed recording findings on your data sheet,
go back to step one and dissect another stem. Insects will not be present in
Copyright 2002. Bernd Blossey. Cornell University
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