CHAPTER V. 



THE EXTERNAL ANATOMY OF A BUTTERFLY. 



(Anosia plcxippus.*) 



As a representative of the large order Eepidoptera, in- 

 eluding the moths and butterflies, the familiar "milkweed " 

 or •'monarch" butterfly, Anosia plexippus, has been se- 

 lected. It is commonly distributed all over the United 

 States. 



PARTS OF THE HEAD. 



THE FIXED PARTS OF THE HEAD. ■ 



In order to study the head of Anosia, it is necessary to 

 remove the scales which almost completely cover it. Rub- 

 bing with a soft, pointed brush, assisted by gentle manipula- 

 tion with a needle or delicate forceps, will soon denude the 

 head.* The antennae may be broken off if in the way. A 

 large part of the denuding may be done while the head is 

 still attached to the body of the specimen ; the denuding of 

 the caudal aspects must be done after removal. If the pro- 

 boscis is tightly coiled, as is probable, the head may be con- 

 veniently held by thrusting a dissecting needle through the 

 center of the coil. 



Compound eyes. — The compound eyes are striking for 

 their large size, each one appearing to constitute about one- 

 third of the head. Examine a portion of the cornea under 



* In addition to the denuded head used for examination it will be advisable for 

 the student to soften and bleach another head ; in the bleached or cleared head cer- 

 tain of the sutures can be more readily seen than in the merely denuded specimen. 

 The bleaching should be done as follows : A denuded head should be boiled for a 

 few minutes in dilute potassium hydrate until the ey s become light-brown; then 

 wash in water and transfer to eau de Labarraque, in which bleaching fluid the head 

 will soon reach the desired clearness. 



