82 
WAT OTL. 
| NOVEMBER 22, 1906 
The experience gained by the form of mounting 
adopted for the 60-inch mirror will be valuable when 
the time comes for the erection of the 1o00-inch mirror, 
and funds will no doubt soon be found when the 
right moment arrives. 
Already the United States is the possessor of the 
two largest refractors and silver-on-glass reflectors. 
This new monster will afford her another means of 
greatly extending astronomical knowledge, which has 
made such vast strides during the last decade owing 
to these increased aids to observation. 
AN EXPERIMENT IN INSECT-EXTERMINA- 
TION.* 
N the year 1900 the sugar-cane planters of Hawaii 
were seriously alarmed by the appearance in con- 
siderable numbers in their plantations of an introduced 
hemipterous insect allied to the cicadas and commonly 
known as the cane leaf-hopper, but designated 
scientifically Perkinsiella saccharicida. Since that 
date the pest has increased to an enormous extent, 
with an estimated loss of many millions of dollars 
t> the planters. Fortunately, the leaf-hopper has a 
certain number of enemies among the insects 
indigenous to Hawaii, since had it not been for the 
extent to which it was held in check by their attacks 
it seems probable that sugar-growing would by this 
time have become absolutely impossible in the islands. 
These indigenous enemies were, however, utterly 
unable to cope in a thoroughly efficient manner with 
the swarms of the leaf-hopper, and it became apparent 
that unless some other means of diminishing its 
numbers were discovered the sugar industry of the 
Sandwich Islands would be practically ruined. 
Accordingly, the officials of the Entomological Divi- 
sion of the Planters’ Association at Honolulu set to 
work with commendable energy and enthusiasm to 
endeavour to find an efficient and satisfactory remedy. 
It appears to have been soon decided that such a 
remedy would most likely be discovered in the form 
of insects which would prey upon the leaf-hoppers 
with greater vigour than any Hawaiian species; and 
in 1903 and the two following years expeditions were 
organised to North America, Australia, and Fiji with 
the view of discovering such insects. 
In due course a number of species inimical to the 
cane leaf-hopper were brought to light, and the 
present elaborate bulletin (of which one part has been 
already briefly noticed in our columns) is devoted to 
the description and life-history of leaf-hoppers and 
their enemies, together with an account of the experi- 
ments which have been made in introducing and 
acclimatising certain of the latter into Hawaii. 
The list of insects parasitic on leaf-hoppers is a 
very long one, and comprises representatives of several 
orders, although the great majority belong to the 
Hymenoptera. For our present purpose attention may 
be concentrated on the few species it has been found 
advisable to introduce into Hawaii. In the case of 
the introduction of such parasites four points are 
essential:—(1) Their effectiveness as destroyers of 
the pests; (2) the possibility of successful transporta- 
tion; (3) the probability of their thriving in the new 
country; and (4) their rapidity of increase when 
introduced. The choice was soon narrowed down to 
certain minute Hymenoptera which feed upon the 
eggs of leaf-hoppers, namely, to species of Anagrus 
and Paranagrus in the family Myrmaridz and to one 
1 “‘Leaf-hoppers and their Natural Enemies.” Edited by R. C. L. 
Perkins. Bulletin No. x of the Experiment Station of the Hawaiian Sugar 
Planters’ Association, Honolulu, 1905-c6. 10 parts. Pp. xxxii + 499; 
illustrated. 
NO. 1934, VOL 75]] 
of Ootetrastichus among the Eulophidae. The 
members of the two first genera complete their life- 
cycles in about three weeks, breed at about the same 
rate throughout the year, and are largely partheno- 
genetic. Ootetrastichus, on the other hand, takes 
fully twice as long to complete its cycle, but produces 
twice as many eggs, and is wholly parthenogenetic. 
Caeteris paribus, the products of the myrmarids at the 
end of six months will, however, be a million times 
more numerous than those of the other genus. On 
the other hand, the ootetrastid is not only more hardy, 
but has the advantage that each individual is bred 
at the expense of the whole contents of the egg- 
chamber of the leaf-hopper instead of destroying only 
a single egg. 4 
Of the four species introduced one of Paranagrus is 
at present the most effective, but the Ootetrastichus is 
slewly but surely increasing in numbers, and_ is 
eventually expected to prove the most effective. For 
further details respecting these interesting and to a 
great extent even at present successful experiments, 
our readers must be referred to the Bulletin ie 
THE FLIGHT PROBLEM. 
HE real ‘‘ flights,’’ not ‘jumps,’? which Mr. 
Santos Dumont has been making at Paris with 
his new aéroplane have directed the attention of the 
whole aéronautical and motor world in the direction 
of the problem of flight. Further, tempting prizes 
have now been offered which will undoubtedly stir 
up other workers to take up the problem and so in- 
| crease the chance of rapidly advancing the progress 
of aérial navigation. 
In addition to the Archdeacon prize of 2o00ol. for 
a half-mile course and to the enterprising offer of 
the Matin of 4oool., which was subsequently increased 
to 10,0001. by public subscription, for the first tra- 
veller who succeeds in covering the distance between 
Paris and. London in 1908, the Daily Mail has now 
ceme forward with the offer, open to the world, of 
10,0001. to the first person who shall fly by aéroplane 
from London to Manchester in twenty-four hours, 
including two stops to take in supplies of petrol. 
Such large prizes will certainly go a long way 
towards giving a strong impetus to the manufacture 
of aéroplanes, and also to the motor industries to 
produce the lightest forms of petrol engines. In 
fact, a great number of people will almost immediately 
set about experimenting with aéroplanes in order to 
compete for the prizes. We read that already Mr. 
Santos Dumont has given an order for a lighter 
and more powerful engine, namely, a 100 horse-power 
motor which will weigh no more than 200 Ibs. 
Since Mr. Santos Dumont’s successes were an- 
nounced, several references have been made to the 
experiments which have been carried out by the 
brothers Wright in America, but very little is known 
about their results, since they, have purposely avoided 
publicity ; according to the views of Sir Hiram Maxim, 
as stated in the Daily Mail, they have a new motor to 
their aéroplane which is twice as effective as their 
previous one, and they hope to ‘‘ fly with it 200 to 
300 miles without stopping.” 
Up to the present time there has not been any 
great inducement for workers to come forward and 
demonstrate publicly the capabilities claimed for their 
machines. The rewards now offered will no doubt 
serve as an incentive to them, and possibly others, to 
enter the arena and prove in open competition the 
efficiency of their designs. 
