THE SQUASH BUG 49 



species the student is referred to " A Manual for the Study 

 of Insects," by Comstock, or to "The Butterfly Book," by 

 Holland. 



THE SQUASH BUG 



Anasa tristes 



Where is this animal found? Is it injurious? At what 

 time of the year is it most abundant? Do you find the 

 three divisions of the body? What are the most pecuHar 

 characteristics of the specimen as you view it from the 

 dorsal side ; from the ventral side ? Measure the length and 

 width. Draw axes. 



The Head. — (i) Look closely for the parts of the head 

 commonly found in insects, viz. : Eyes, ocelli, and antennae. 

 How many ocelli? How may segments in the antennae? 



(2) On the ventral side raise the sharp, jointed beak 

 or proboscis. How many segments has it? It is composed 

 of a combination of mouth parts specialized. Of what use 

 can this specialization be ? Can you distinguish the different 

 mouth parts? 



(3) Find the /a&rwOT at the base of the proboscis. Lying 

 in a groove on the upper part of the beak are two pairs of 

 hairs. Lift them up with a needle. The shorter pair rep- 

 resent the mandibles, and the longer, the maxillae. 



(4) The sheath which remains is made up of the labium 

 and the labial palpi. This accounts for the segments found 

 in it. 



For what is the proboscis used? How does the animal 

 obtain its food ? What is its food ? 



The Thorax. — (i) Observe the relative sizes of the 



STU. IN ZOOL. — 4 



