SPECIAL EXHIBITS. 



ENLARGED MODELS OF INSECTS, AND OF INSECTS AND INJURED 



PLANTS. 



MALARIA MOSaXJITO. 



AnopJideti maculipennis Meig. 



Enlarged model. This and other species of Anopheles are the only known trans- 

 mitters of human malaria. The parasitic organism causing malaria inhabits the red- 

 hlood cells of human beings. It is taken with the blood into the stomach of the 

 mosquito. There it undergoes a sexual development, reproduces, and the offspring 

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



YELLOW FEVER MOSQUITO. 



Stegomyia fasciata Fab. 



Enlarged model. This mosquito transmits yellow fever, and it is now the opinion 

 of the best-posted experts that only through its bite can one contract this disease. 



SALT MARSH MOSQUITO. 



Culex ^ullicitans Walk. 



Enlarged model. This mosquito is not known to carrj' any disease, but is very 

 annoying at many seaside resorts. 



THE HOUSE FLY. 



Musca domestica Linn. 



Enlarged model. The house fly is not merely a nuisance, but also acts as a carrier 

 of many diseases, especially of typhoid fever in the United States. 



HESSIAN FLY. 



Mayetiola destructor 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 of the adult Hy, and of an infested stalk of wheat showing the 

 puparium or so-called "flaxseed," which encloses the pupa stage of the insect. 



Two natural-size models, one representing a healthy, unaffected .\oung wheat 

 plant to contrast with the same attacked by the Hessian fly; the other illustrating 

 the effects of the attacks of the Hessian fly. 



THE SILKWORM. 



Bomhyx {Sericaria) mori Linn. 



Enlarged model of the larva, showing its complete anatomy; the muscles, nerves, 

 trachete, viscera, the silk apparatus in its whole extent, the silk-secreting gland, and 

 the glai\d discovered by Auzoux, which secretes a liquid the use of which is most 

 probably to convert the silky matter into insoluble threads. In one of the prolegs 

 may be seen the muscles which move the claws and sucking disks whitili enable the 

 animal to walk with its true feet in the air. 



Enlarged models of the moths, male and female. In each model is shown the 

 atrophy of the digestive tube and the development of the marvelous organs by which 

 the species is perpetuated. (After Auzoux.) 



103 



