42 SANITARY ENTOMOLOGY 



growing against these insects from the sanitary standpoint. Some of 

 these insects contain substances in their bodies which are highly toxic, as 

 for instance Sitophilus granarius, the granary weevil, contains the 

 poisonous substance cantharidin. There are numerous instances of the 

 sickening of animals from eating weevily grain. Still more important is 

 the fact that where grain is accessible both to rodents and insects, certain 

 parasitic worms pass out in the feces of the rodent in the egg stage, 

 are eaten by the insect larvae in the grain, pass part of their life cycle 

 in the insect, and the insect is then possibly eaten by a rodent, in which 

 the worm completes its life cycle ; or sometimes in our breakfast foods 

 we eat these parasitized insects and become infected with the worms. For 

 example, the rat tapeworm, Hymenolepis dimvnuta (Rudolphi) infests 

 various species of rats, but sometimes is found in man. Joyeux has 

 proved that its commonest intermediate host is the meal moth, Asopia 

 farmalis, which becomes infected by eating the tapeworm eggs, in the 

 larval stage. Grassi and Rovelli found the cysticercoid in the larva and 

 adult of this moth and also in the earwig, Anisolabis annulipes and the 

 beetles Akis spinosa and Scaurus striatus. Joyeux found that the adults 

 of the granary beetle, Tenebrio molitor, easily took up the eggs. A 

 cysticercoid or larval stage resembling the mouse tapeworm Hymenolepis 

 microstoma (Dujardin) has been found by Grassi and Rovelli in the 

 beetle Tenebrio molitor. 



The whole problem, therefore, of the control of stored food product 

 insects is of vital importance to the manufacturers of food. 



Syrup factories, sugar mills and refineries, ice cream factories, cream- 

 eries, and candy factories offer great attractions to flies which may 

 alight on the exposed products and deposit with their feet, or in their 

 vomit or excreta, germs of disease taken up elsewhere, perhaps days 

 before when the fly was a larva breeding in excrement, and these germs 

 may find the sweets excellent culture media for extensive growth. Extraor- 

 dinary means must be devised to keep flies away from such products. 



Packinghouses offer abundant attractions to many kinds of insects, 

 many of which are serious disease carriers. 



Railroad trains are the means of conveying from place to place 

 disease-carrying mosquitoes, flies, roaches, fleas, lice, bedbugs, and mites. 

 Fumigation of railway cars is an essential entomological control measure. 



Dairies are often found to be the foci of the spread of typhoid fever, 

 and knowing the propensity of the house fly we can see how readily it 

 can carry the organisms from the stools of a sick person to the milk 

 pails in the dairy. There needs to be rigid control of flies in all dairies. 



These are but examples of many industries which have problems in 

 sanitary entomology. 



