Evening star., 1953-08-07
Radioactive Bug Killers
To Show Insect Range
Isotopes Con Determine
Fly Population Density
By Thomos R. Henry

Entomologists of the Agriculture De-
partment are planning new uses of
radioactive insects and insecticides to
find out how fast and how far insects
fly, how a poison kills bug, and Just
how some insects-particularl house.
flies and ckroaches-develop resist
ance.
Since insects do great damage them
selves and often carry diseases Of plants,
men and animals, knowledge Of how
far they move in q known time is of
great help in their control. An insect
tagged with radioactive iSotope can
be detected by a counting mechanism
even when out of sight-for instance,
under the bark of tree.
Similarly, tagged insecticide can be
traced through bugs small body to
reveal what physiological changes take
place, and how resistance is developed.
Radioactive blow flies have been
traced in traps 20 to 80 miles from the
point Of release.
DR.. F. H. Babers. Agriculture Depart
ment chemist, will use radioisotopes to
learn how various insecticides kill bugs.
After supplying an inSect-killing mate
rial tagged with radioactive atoms to
such an insect he can follow its route
through the body and through the nerv-
Gus and digestive systems until its final
eXcretion or storage. Photographic
plates and other radiation detection
devices will give progressive pictures
of the penetration of the poison.
Method Used in Florida.
Radioactive isotopes also can be used
to determine the abundance of insects
in any particular area. When radio
active females, which lay radioactive
but otherwise normal eggs are released,
the ratio OF radioactive to normal egg
masses later collected gives fair key
to this abundance. The method now
is being used in Florida to determine
the density of the screw-worm popu-
lation.
The iSotopes may be used later to
find out how systemic insecticides are
distributed in plants. They are being
used IN studies of how hive-destroying
bee diseases spread and of the complex
relations various castles of bees within
the hive have to the production of
honey.
The fantastic Pycnogonida, or sea
spiders, have been photographed by
navy photographic Office scientists on
tne sea moor two miles under the North
Atlantlc The pictures show these
nlghCmarlSh creatures crawling over
the mud. They are just pairs of long
IegS'-Sometimes eight, sometimes 10,
sometimes IL. These legs may reach a
length of two or three inches, and are
attached to body which seems only
an extremely minute tail covered with
chltlnouS shell. Along the New Eng
Iand coast they are called nobody
CRABS. 1n>addition to the walking legs,
lnoSt sea spiders have two shorter pairs.
one pair tends to be modified into
plncer-llke jaws. The other is provided
With tiny hooks on which the males
carry eggs and young.
Related to Crabs.
The deeper they 60 the longer tho
legs 10 keep them off the Sea-bottom
mud Ihese creatures probably are
more closely related to horseshoe
crabs than to any other animal. They
might be considered at some inter-
mediate point between crabs and
spiders. A greater part of the diges-
tive organs are in the tops Of the long
legs. Females lay the eggs and then
hang them in clusters upon hooks on
the legs OF the males. Here they are
carried until they hatch. In some
species the young cling to the fathers
legs until they are fully developed.
The head contains four simple eyes
and the extremely minute brain.
The Pycnogonida are almost all bot
tom-dwelling animals. Some, how
ever. come to the surface in the breed
ing season, where they tread water
with their long legs. A few live at
tached to seaweed in the Sargasso
Sea. The largest have a leg spread
OF three or four inches but most are
quite minute. They are especially
abundant on the sea floors of the sub
Arctic and Antarctic. There are more
than 500 known species.
They supposedly live on detritus
which sinks from the surface.