94 INSECTA 



3. Head. 



(1) Antennae. 



(a) Location? 



(b) Number of segments? 



(c) Use? 



(2) Compound Eyes. 



(a) Location? 



(b) Size? 



(c) Shape of facets? 



(3) Simple Eyes. 



(a) Location? 



(b) Number? 



(4) Mouth-parts. Straighten out the proboscis which is 



bent back under the head, and examine it with a good 

 dissecting microscope or with the low power of a 

 compound microscope. 



(a) The tongue is the labium modified or the under lip, 



and the divisions at its end are the labial palpi. 

 Are they smooth or rough? 



(b) Mandibles. On the head near the base of the tongue 



look for the slender, rudimentary mandibles. 



(c) Maxillary Palpi. On the shaft of the tongue find 



the hairy, segmented maxillary palpi. 



(d) Sketch the mouth-parts as you see them. Compare 



with a good cut and name the parts shown in your 

 figure. 



(e) Are the mouth-parts adapted for biting, sucking, or 



lapping? 



4. Thorax. 

 (1) Wings. 



(a) How many developed wings? 



(b) How are they arranged when at rest? Show by 



sketch. 



(c) Look behind the wings for a pair of scales or mem- 



branes — the alulets. 



(d) Under the alulets look for a pair of pin-like append- 



ages ending in a knob. These are called ''balan- 

 cers," and it is believed that their function is sen- 

 sory. 



