A simple device to clean insect specimens for museums and scanning electron microscopy

2 Pages·1991·0.86 MB·

by  J Jenkins

PROC. ENTOMOL. SOC. WASH.
93(1), 1991, pp. 204-205
Note
A Simple Device to Clean Insect Specimens for
Museums and Scanning Electron Microscopy
Insect specimens are often contaminated
with debris that obscures structures of in-
terest. Scales and hairs adhere to specimens
taken from malaise traps or by other col-
lecting methods that capture Lepidoptera
with other insects. Dust accumulates on in-
sectsboth in lifeandas mounted specimens
in collections. When mounting insects for
scanningelectron microscopy, fragments of
dissected structures often adhere to the
specimen. Below I described a simple, in-
expensive device that uses a fine jet of air
to efficiently remove loose debris without
damaging specimens.
The device (Fig. 1) consists ofa one liter
filteringflask,aone-holerubberstopper(no.
mm
8), latex rubber tubing (6.4 I.D., ca. 80
mm
cm long), plastic tubing (6.4 I.D., ca.
mm
70 cm long), glass tubing (8 O.D., ca.
28 cm long), a small quantity of polyester
aquarium filter fiber, and a modified dis-
cm
posable glass Pasteur pipet (14.6 long).
Latex tubing facilitates manipulation ofthe
pipet; plastic tubingis less likely to collapse
and block air flow to the device. The poly- vent hole
esteraquarium filterfiberremovesmoisture
andothercontaminantsfromtheairsupply.
The pipet (Fig. 2) is modified as follows: tip
Reduce the diameter ofthe hole in the tip
mm
ofthe pipet to about 0.25-0.5 by pass-
ingitthroughthe flameofa Bunsen orFish-
erburner.Forsafety,useprotectiveeyewear,
and before making the vent hole attach a
length of tubing to the pipet to keep your
face away from the flame. Make the vent
hole by holding one side ofthe shoulder of
thepipetintheflame. Whentheglassbegins
to glow, blow through the tubing attached
to the pipet until a bubble begins to swell
from the areabeing heated. Continue blow- Figs. 1-3. Device forcleaninginsectspecimens. 1,
inguntil thebubblebursts, thusformingthe Complete device. 2, Modified pipet. 3, Holding the
vent hole. Polish the edge ofthe vent hole pipet.
VOLUME 93, NUMBER 205
by passing it through the flame. The final becoming great enough to damage speci-
diameter ofthe vent hole should be about mens. Loose debris is blown off"ofa spec-
3-4 mm. Finally, bend the pipet near the imen by directing thejet toward the area to
tip by passing it through the flame. A low be cleaned. This can be done under a dis-
flame works well for modifying the tip of secting microscope. Debris that is glued to
the pipet; a hotter flame is best for making a specimen by oil or other such substances
the vent hole. usually cannot be removed.
Assemble the device as shown in Fig. 1 Because ofthe low volume ofair used, it
and attach the plastic hose to a source of isunlikelythat pressurewithinthe flaskwill
compressed air. In many laboratories com- become great enough to break the flask.
pressedairisavailable from stopcocksbuilt Moreover, the stopper, ifnot placed in the
flask with excessive force, acts as a safety
into the benches.
valve. However, asanadded precaution the
Air passing through the tip ofthe pipet is
flask should be wrapped with nylon-rein-
used to clean specimens. Use very low vol-
forced tape.
umes ofairfrom thecompressedairsource.
Additionally, by reversing the direction
The optimal volume depends on the di- ofairflowthrough thedevice, itcanbe used
ameter of the hole in the tip of the pipet. to pick up and manipulate small delicate
The air passing out ofthe vent hole should objects. For this purpose, install the device
be barely detectable for pipets with tips re- onto a vacuum line.
duced to 0.25-0.5 mm. John W. Heckman, Center for Electron
Air is forced through the tip ofthe pipet Optics, Michigan State University, East
by covering the vent hole with your index Lansing, suggested the method for making
finger (Fig. 3). Because the hole in the tip is a vent hole in the pipet. An earlier draft of
much smaller than the vent hole, air pres- the manuscript was reviewed by Guy L.
sureincreasesintheflaskwhentheventhole Bush, Judith M. Sirota and Frederick W.
is covered. Simultaneously, the velocity of Stehr, Department of Entomology, Michi-
the airleaving the tip ofthe pipet increases. gan State University, East Lansing, and an
When cleaning specimens, use short bursts anonymous reviewer. Their assistance is
ofair by opening and closing the vent hole gratefully acknowledged.
atregularintervals, orbyonlypartiallycov- John Jenkins, Department of Zoology,
ering the vent hole. This will prevent the Natural Science Building, Michigan State
stopper from being blown out of the flask University, East Lansing, Michigan 48824-
andwillalsokeepthevelocityofthejetfrom 1115.