Santa Clarita and Northern Los Angeles County Area Butterfly and Moth Site
Collecting Equipment Projects, Ideas and Sources
Super Gigantic "Net-a-Saurus Rex", AKA "Sky Sweeper" Collecting Net
Everyone who collects Lepidoptera has swung a net at a Lep and missed.
At one point, we've all thought "If I only had a bigger net..." Well,
here it is. Originally conceived to make catching male Saturnia
albofasciata remotely possible, it's also proven effective at increasing
the odds of capturing other difficult to net bugs such as Hemileuca
species. This particular specimen is the quick and dirty prototype of
the only Netasaurus Rex in existance (at present). I had planned to make
a "nicer" one and to show construction detail photos along the way but
time has been short and demand high!
See the video on
Besides improving the collectors odds, this net is intended to be
lightweight, rigid, cheap and easy to make. You can get just about
everything from your closet, garage and/or local Wal-Mart type store.
Basic materials list:
1 34" diameter Hula-Hoop (Wal-Mart, $1.98)
1 wood or aluminum (preferably telescopic) handle ($3 - $24)
1 wire clothes hanger/stiff steel wire (closet, shed, etc)
4 yards of tulle netting, any color (Wal-Mart, <$4)
1 roll duct tape
1 tube "Alex" caulking
1 roll waxed paper
Of course you may improvise and change the specs as desired although the
measurements will have to be adjusted accordingly if the net diameter is
changed. While there's lots of room for modification, I highly recommend
that one design feature NOT be changed - the net handle connection at
two points (top and bottom) of the net ring. Most "standard" nets
connect to the handle only at the bottom of the net ring. However, a
traditional handle connection to a net ring this large won't be strong
enough to withstand the load. You'll find that the weirdness of the
handle crossing the net opening is well worth the gain in strength and
rigitidy as soon as you sweep this monster through the sky. As of this
writing I've never had a specimen damaged from contact with the cross handle
and sometimes I even find my specimens conveniently knocked-out in the net
because of it!
measuring tape/long straight-edge
drill with 3/16" (more or less) bit
Here are some shots of the whole assembly with handle extended and
collapsed. Yes, it's ugly and made with the cheapest materials ever.
While unattractive, it's quite functional and certainly proved the
concept viable. A 4-foot straight-edge is included for scale. No doubt
about it - this is a really BIG net!
This cheesy (what can I say) MS Paint diagram shows the basic assembly
and dimensions, which I will make reference to as this text progresses.
I recommend that you take your own measurements before cutting anything
to size, just to be sure no materials go to waste.
Let's start with the net bag, since it's assembled using a glue that
will need to dry. The bag is made from the most arial netting I could
find - "tulle" netting from wal-Mart. It costs $0.75 to $1 per running
yard and is usually about 60" wide. This netting is extremely lightweight
and allows air to pass easily so it won't slow your swing much. The
downside is that it's not very strong and will rip to shreds if you snag
any sharp objects.
You will need two pieces of netting, cut to the dimensions shown in the
diagram above. If you changed the size of your net ring then you'll need
to re-size your net bag. To calculate the net ring side of the bag (side
D), use the formula [pi x Dia /2]. Example: a 34" diameter ring has a
circumference of 107" (3.14 x 34). (I like to round-up AND add a few
inches). Since the net bag is made from two halves, you divide that
circumference by 2 and get about 54" (I recommend 56" or better for the
34" dia. net ring shown). As far as the net bag measurements - WHEN IN
DOUBT, MAKE IT BIGGER than you need. A larger-than-needed net bag will
fit a bit loose and "baggy" while one which is too small simply won't
work. Play it safe - make your D side halves 56" or better.
Note that side "D" is not cut straight across but is curved.
Without going into too much geometry, this is because we're dealing
with a 3 dimensional cone rather than a simple 2-D triangle. If you
don't cut the top of the bag this way it will fit the net ring funny (but
should still work). The length of the bag should be about twice the
diameter of the ring so that enough net bag can be folded over the ring
to prevent a captured specimen from escaping. Longer is better.
Once you have both halves of the net bag cut, fold about 2.5" of the top
edge (side "D") of one net bag half over onto itself and glue it down
using the caulking. Note that due to the weird curve of side D that
there will be extra material which whon't want to fold over neatly. Just
do the best you can with it - it's OK if it's a little baggy.
Glueing can be done an any flat surface covered with strips of waxed
paper to prevent it from sticking to the work surface. The seam (glued
area) should be about 1/2" wide and thick enough to make a rubbery,
contiguous band which cannot be torn apart when dried. For details on
glueing net material with caulking, see my other project -
"making your own sleeves".
Fold-over and glue side D of the other net bag half, and let the glue
dry. See the pictures below for reference. When the glue dries, you
should have a 2" dia. tube of folded-over net which the net ring will
slip through. When side D dries on both net bag halves, glue the two
halves together on 3 sides (A, B and C), again on a flat surface covered
with waxed paper, and let it dry.
The net ring (a Hula-Hoop from Wal-Mart) costs less than $2 and is
basically a long tube, bent-around in a circle, the ends of which are
joined together with a smaller tube and a couple of pins. It also
contained some small plastic beads inside to make it rattle when moved.
Since I had to open up the ring to slide it through the net bag anyway, I
opted to remove the rattles too. I figured I would look gooney enough
swinging such a large net without rattles attracting even MORE
I found an unused telescopic aluminum mop/utility handle in my shed
which measured 36" collapsed, and 70" extended. It's lightweight, very
strong, and "twist-locks" in any position.
The handle end (outer tube) has a hole in the end (for hanging it for
storage). This hole made the perfect place to slide the cross-brace
connector though. The cross-brace is a critical design feature, used to
bind the top end of the handle to the net ring AND provide
tortional/longitudinal rigitidy. Without it, the net would be weak and
The cross-brace connector (figure E in the diagram) is basically a
length of stiff wire (brown) which is threaded through a hole in the end
of the net handle (black), and then secured to the net ring (blue) on
both sides with duct tape (grey) or similar. I used a short length of
stiff steel wire, folded over once (doubling its thickness). If your net
handle doesn't have a suitable hole at the end, you will need to make
one. Make the hole only as large as necessary to fit the cross-brace
though (a larger hole makes a sloppy and weak connection)and be sure to
leave enough material at the end to prevent splitting/cracking
(especially if you use a wooden handle).
The photos below show my very messy but strong and functional cross-brace.
Now that your net bag is dried, and handle/net ring are prepared, you
should be ready to slip the net bag onto the ring. You'll need to
disconnect the ring joint (or cut the ring if it's one piece) in order
to get the bag on. Once the bag is on, reconnect the joint. If you had
to cut the ring, place something stiff inside the tube and tape it up
really good. Rotate the ring so that the joint is at the 3 O'clock or 9
O'clock position - as far away as you can get it from the 12 O'clock and
6 O'clock positions where the net handle will connect. This will help
take the stress off of the naturally weak joint. Attach the handle to
the ring using duct tape or wire at the top (12 O'clock position) [Ref.
fig. E in the diagram] and strong wire (I used a clothes hanger) at the
bottom (6 O'clock) [Ref. fig. F in the diagram]. You'll need to cut away
a little of the net bag at the attachment points in order to make the
connections. Cut only as much as needed. See the photos below..
Hopefully, the photos will fill-in any gaps in the instructions. I hope to
one day re-do this page with proper documentation but for now, this should
get you going!
Have success or failure with this or a similar project? let me know!