Evening star., 1952-08-25
Eurth's Insect Varieties
Moy TotoI 10 Million
$4,000 Kinds Are Known;
1000 More Found Yeorly
By Thomos R. Henry

7UUO More Found YeuTIy
By Thomos R. Henry
There may be as many as 10 million
different kinds Of insects in the world.
More than S2.000-of which at least
10000 are decidedly injurious to man
have been described already for the
United States and Canada. About O
million species and varieties are known
In the world. Bugs" constitute from
20 to 80 per cent Of all known animals.
BY far the greater part Of the insect
family remains unknown. New types are
being discovered the world over at q
rate Of almost 1000 each year.
Such are the figures Of DIR. Curtis w.
Sabrosky Of the United States Bureau
Of Entomology in the annual year
book Of the Department Of Agriculture.
devoted entirely to scientific reports
on the creatures which even now are
mans chief rivals for dominion over
this planet.
About two-flfths Of all known in
sects are beetles. Moths. butterflies, ants,
bees. wasps and flies constitute an
other two-flfths.
kent I'm Control by Nature.
The number Of individuals within
these insect groups Is, DR.. SabriSky
points out, inestimably astronomical.
for nearly all bugs have enormous re-
productive powers and soon would run
every other form OF life OF the earth
II 1t were not for balancing forces Of
nature. For example. says the report:
I'm one summer season from April
to August the descendants Of one pair
of house flies, II all lived and reproduced
normally, would make total Of 191,-
900 ZOO. 900 .000, ,000,0 900. But fortunately
reproduction does not usually 60 on at
full speed. Other insects, birds, weather,
insecticides and diseases take toll Of
the eggs that are laid and the young
that are born"
Compared with some other insects.
the fly is quite modest progenitor.
Calculations have been made on one
seasons progeny Of cabbage aphid,
one Of the great family Of plant lice.
There is an average Of Al young per
female and Is generations between
March and October. Between March
and October the descendants Of one
female would amount to 100000
O00, 900, ,000, 900, ,000, 900 individuals. Some
closely related forms in the South may
produce two or three times as many
progeny.
Ant Lays $40 Eggs . Day.
Some insects lay eggs continuously
over long periods. Ant queens have been
known to lay as many as $40 q day.
From 5000 to 1000 eggs day is not an
unusual record for termite queens, and
each queen may live from Is to 80 years.
One East African termite has been OBJ
served laying eggs at the rate Of one
every two seconds. or $4,000 day. but it
Is not known how long she could keep
going at this rate.
curious method Of insect reproduc-
ton is reported by DR.. Sabrosky. This
is "polyembryony. process whereby two
or more young result from a single egg.
In its simplest form. one egg divides in
two. just as identical twins originate in
the higher animals. The parts Of the
original egg may. keep on dividing, In
some species as many as 2, 500 insects
finally result from single egg"
Ordinarily. nature keeps the insect
hordes fairly well under control, but
sometimes there is a slip-up and only
then does man realize the tremendous
forces Of the big world which may be
loosed against him.
Such occasions were the grasshopper
invasions Of the Plains States about 80
years ago when one Nebraska observer
recorded q swarm q half high,
100 miles wide and 800 miles long. Il
left fields barren as II swept by FIRE.
In that one great swarm, 1t Is esti-
mated, there were more than 124,000.-
100000 individuals. The column moved
for about six hours at rate Of five
miles an hour.
Migrate in Huge Swarms.
Especially striking. says the report,
are the migrations of butterflies.
Millions may fly for days as far as
1000 miles and the migrating swarm
may be several hundred miles in width.
One Texas observer recorded q migra-
ton Of snout butterflies which were so
numerous that an average Of about
1.250.000 per minute few across front
$50 miles wide. The migration contin-
ued at the same level Of intensity for
18 days.
Certain wire worms have been found
In numbers calculated from 3 million
to rs million per acre. From samples
taken to depth Of i've inches in North
Carolina. it was calculated that there
were approximately 124 million animals
in the soil per acre. OF these, nearly
80 million were mites. 28 million spring.
tails and AZ million other insects.
In q scrub oak forest in Pennsyl-
vania, workers found an average Of
9,759 per square foot Of surface. That
figures out to AS million per acre."