POISONOUS INSECTS AND THEIR RELATIVES 435 



the hair. When these nettling hairs are mingled with a 

 drop of blood on a slide under the microscope, there is a 

 profound effect. The strings of red blood corpuscles are 

 broken apart and each corpuscle becomes greatly 

 changed in shape. It is probably safe to say that 

 similar changes take place in the blood when these hairs 

 penetrate the skin, thus producing the dermatitis. 



Many remedies have been advertised and recommended 

 for the brown-tail rash, some of which have afforded 

 relief. For a time, the liberal use of vaseline was 

 recommended, but of late certain mixtures producing a 

 cooling effect have been more commonly used with more 

 satisfactory results. External applications of alcohol and 

 witch hazel afford considerable relief. According to 

 Howard, a mixture compounded after the following pre- 

 scription has been tried repeatedly with good effect : — 



Menthol grains 10 



Zinc oxide drams 2 



Aq. calcis ounces 8 



Acid carbolici drops 15 



For nettling insects, in general, weak solutions of 

 ammonia or ordinary baking soda moistened with water 

 and applied to the affected areas in a paste will allay the 

 irritation and give relief. 



The large order of insects composed of the beetles, 

 Coleoptera, contain very few poisonous forms existing in 

 this country and very few in the world. It is said that 

 some beetles are capable of inflicting severe bites. The 

 saw-toothed grain beetle, Silvanus surinamensis , has the 

 reputation of biting people. The larva of a beetle in 

 Angola, Africa, is said to be able to inflict wounds on the 



