PARASITICIDES 37 



d. Notice the comparative absence of hairs on the body of 

 this species. 



e. Notice the mouthparts. How does the spider "bite"? 

 Draw the specimen. 



B. Our commoner scorpions are represented by the three 

 genera, Centrums, Hadrurus, and Uroctonus. 



Examine a specimen for the following characteristics: 



a. What is the form of the moiUhparts? 



b. What is the form and function of the chelicerce? 



c. How many walking appendages has the scorpion? 



d. Examine the sting at the tip of the abdominal appendage. 

 Draw the specimen. 



C. Examine specimens of the whip scorpion (Order Pedipalpi). 



'' //XV2MA/U < ..' 



EXERCISE 22 



A^n 



PARASITICIDES 



Poisons and repellents. The student should familiarize him- 

 self with at least a few of the commoner materials used to de- 

 stroy or repel parasites of man and the domesticated animals. 

 Samples of each of the following materials should be examined,, 

 and notes should be taken describing the physical properties, 

 such as color, smell, weight, whether liquid or solid, whether 

 homogeneous or a mixture, etc. Caution! Do not taste these 

 materials; they are Poisons. 



a. Nicotine (tobacco decoction) is used as a dip for the 

 destruction of scab mites on sheep and also against lice and 

 mites on other animals which do not vomit. Nicotine is a poison. 

 The proportion of tobacco decoction used depends on the 

 nicotine content. " Black leaf 40," a commercial brand, has a 

 high nicotine content. One pound of a forty per cent solution of 

 nicotine to 100 gallons of water (soft water) would make a dip 

 answering the requirements of the U. S. Bureau of Animal 



