124 



SPECIAL EXHIBIT OF MODELS OF INSECTS AND OF PLANTS AND 

 INSECTS AFFECTING THEM. 



YELLOW FEVER MOSQUITO. 



Stcgoiiij/iafdscidta Fal). 



Enlarged model. This mosquito transmits 3"ellow fever and it is 

 now the opinion of the best-posted experts that only through its bite 

 can one contract this disease. 



MALARIA MOSQUITO. 



AnopJieles mucuUpeimis Meig. 



Enlarged model. This and other species of Anopheles are the 

 only known transmitters of human malaria. The parasitic organism 

 causing malaria inhabits the red-blood cells of human beings. It is 

 taken with the blood into the stomach of the mosquito. There it under- 

 goes a sexual development, reproduces, and the ott'spring are carried 

 with the mosquito poison into the circulation of healthy human beings. 



SALT MARSH MOSQUITO. 



Culex soUicitans Walk. 



Enlarged model. This mosquito is not known to carry an}" disease, 

 but is very annoying at many seaside resorts. 



THE HOUSEFLY. 



Musca domestica Linn. 



Enlarged model. The housefly is not merely a nuisance, but also 

 acts as a carrier of many diseases, especially in the United States of 

 typhoid fever. 



HESSIAN FLY. 



Cecidomt/nt dedrnctor Say. 



One of the most injurious enemies of wheat in the Northern and 

 Central States. The larva attacks the stem. The average yearly 

 damage to the wheat industry in this country from this insect is 

 $60,000,000. 



Enlarged models are exhibited of the adult fl}", and of an infested 

 stalk of wheat showing the so-called " flaxseed" stage of the insect. 



Two natural-size models are exhibited, one representing a healthy, 

 unaffected young wheat plant to contrast with the same attacked by 

 the Hessian fly; the other illustrating the effects of the attacks of the 

 Hessian ffy. 



GRAPE-VINE TRUMPET-GALL. 

 Lasioptera viticola O. S. 



Model in wax of the abnormal growths caused by the sting of a 

 minute dipterous insect not infrequently observed on the leaves of the 

 grape. 



