108 The West American Scientist. 
menters have shown that serious blood maladies may be trans- 
mitted by the mosquito. 
Certainly, therefore, any suggestion however remote, of a 
means of decreasing the numbers of or exterminating these pests 
should be followed with all possible skill and patience. 
I have observed dragon flies gathering in scores around my 
camp in Minnesota to feed on the mosquitoes. I recently: saw a 
dragon fly that had devoured over thirty house flies still voracious 
for more. Entomologists have observed the larve of the dragon 
fly swallowing undeveloped mosquitoes in large numbers. 
Now may we not have in the active, voracious, harmless “mos- 
quito-hawk,’’ an agency for greatly diminishing the numbers 
of the smaller insects? 
Professor Baird’s success in producing millions of healthy fish 
in a few laboratory boxes and jars, the propagation of silkworms 
by scores of millions from eggs carried half around the world to 
Italy, the success of the plan for breeding foreign humble-bees 
- in Australasia to fertilize the red clover,—these and many other 
similar facts seem to show that scientific methods have reached a 
stage where it is reasonable to hope that a plan may be devised 
whereby whole tribes of noxious insects may be exterminated by 
the artificial multiplication of their innoxious enemies. 
For the purpose of drawing the attention of entomologists to 
the subject mentioned, I have placed in the hands of Morris K. 
Jesup, Esq., President of the American Museum of Natural His- 
tory, New York city, $200, to be paid by him in three prizes of 
$150, $30, and $20, for the three best essays based on original 
observations and experiments on the destruction of mosquitoes 
and flies by other insects. 
The following suggestions are made as to the direction in which 
the investigation should be carried and the essay formulated. 
I. Observations and experiments upon various insects that 
destroy mosquitoes and house flies, stating the method of and 
‘capacity for destruction. 
2. Observations and experiments to determine the best dragon 
flies to be artificially multiplied for the two above named objects— 
probably species of Aeschna, Libellula, or Diplax. 
3. Give detailed statements of the habits and life history of the 
species chosen, based on original and careful experiments and ob- 
servations. 
4. Suggest a plan for breeding the insects in large numbers 
with a sketch of apparatus, and estimated cost of producing them 
per thousand. 
5. Formulate a plan for using the insects in the larva, pupa, 
or perfect state for the destruction of mosquitoes and flies, (@) in 
houses, (8) in cities, (c) in neighborhoods. ; 
In awarding the prizes clearness of statement obtained by ac- 
companying sketches and new and purely scientific facts in the 
