CHAPTER XXXIII 

 THE HYMENOPTERA 



The insects which belong in this large order have no general common 

 name, but many of them are well known as bees, ants and wasps. The 

 larger portion of the group, however, consists of small insects seldom 

 noticed except by those looking for them. 



Most Hymenoptera have wings when adult. These are four in num- 

 ber, membranous, and the front pair is the larger. They have rather few 

 cross veins as a rule, and in some cases nearly all the veins are missing. 

 The two wings on the same side of the body are united by a row of hooks 

 along the middle part of the costa of the hind wing, which catch in a fold 

 of the membrane on the hinder margin of the wing in front, the two wings 

 in this way acting together and much as though they were one. The 

 structures uniting them are called the frenal hooks or hamuli, and the 

 f renal fold. 



The body in insects of this order may be quite large and stout, as in 

 the bumblebees; or long, being two or more inches in length in some trop- 

 ical wasps, but most of them are much smaller insects and in some the 

 body may be only about a fiftieth of an inch long and the entire animal 

 almost microscopic in size. The first abdominal segment is very closely 

 and firmly joined to the thorax, to which it apparently belongs. In a 

 few families the front end of the second abdominal segment is as large as 

 the rest of this portion, and the connection between the first and second 

 segments is full-sized, but in most of the groups the front end of the second 

 segment is constricted to form a small, stalk, pedicel, or petiole which 

 connects the rest of the abdomen with the first segment. This condition 

 is a deceptive one, leading to the idea that the constriction is, as is true 

 of most other insects, between the thorax and abdomen rather than be- 

 tween the first and second segments of the latter. The first segment, 

 closely joined to the thorax is called the propodeum or median segment. 

 The petiole in nearly all cases joins the propodeum close to the lower side 

 of the body. 



Over the base of each fore wing except in the ants, is a small, arched 

 scale called a tegula, which roofs over the place where this wing articulates 

 with the body. 



In the female Hymenoptera an ovipositor, used either for making 

 holes in which to deposit eggs, or modified to become a weapon, is almost 

 always present. When developed for its original purpose as an organ 



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