920 



AN INTRODUCTION TO ENTOMOLOGY 



Wings of a braconid. 



and third abdominal segments inflexibly joined together. There is 

 usually also a vein crossing the large cell situated below the stigma. 

 This is wanting in the Ichneumonidse. The braconids as a rule are 

 smaller than the ichneumonids. Many of the North American 

 braconids large enough to be confused with ichneumonids have black 



wings and a red and 

 black body, a color 

 combination rare in 

 the latter group. 



In this family 

 are included proba- 

 bly over two thou- 

 sand North Ameri- 

 can species. The 

 great majority are 

 parasitic upon 

 caterpillars. The 

 rest attack mainly 

 thelarv^ae of weevils, 

 leaf-beetles, borer 

 beetles, and cyclorrhaphous Diptera. The subfamily Aphidiinse 

 attacks plant lice, the subfamily Ichneutinae sawfly larvae, and the rare 

 subfamilies Paxylommatinse and Neoneurinae are ant parasites. A few 

 Alysiinae are secondary parasites. 



Because of the excellent characters offered by their venation, the 

 braconids are easier to classify than the ichneumonids, yet because 

 of their small size they have escaped the attention of the average 

 entomologist so that many facts about them are still to be learned. 

 About eighteen subfamilies are now recognized, of which the Alysiins, 

 Aphidiina?, and Paxylommatinae are sometimes treated as separate 

 families. Some of the larger and more interesting groups are discussed 

 below. 



The subfamilies Vipiinas (= Braconinae), Spathiinae, HecabolinEe, 

 Doryctina?, Hormiinae, and Aleiodinae are all closely related and per- 

 haps should be made a single subfamily. In these the clypeus is 

 arched upwards and the labrum is very concave so that there is a 

 circular opening above the mandibles, hence the name Cyclostomi 

 which is applied to this group. Members of the Cyclostomi usually 

 parasitize caterpillars or beetle larv^ae living in tunnels or nests. The 

 female permanently paralyzes the host larva by stinging it with her 

 ovipositor, then deposits one or several eggs on its body. She may 

 stop to lap up the juices exuding from the ovipositor wound. The 

 eggs hatch into lar^^ae which feed through holes cut in the skin of the 

 host. When mature, they spin cocoons near the host remains. 



The subfamily Cheloninse has the abdomen in the shape of an 

 oval shield which looks like an inverted bath tub or a turtle shell. 

 In some genera there are evident sutures separating the three tergites 

 which make up the dorsal shield. In this subfamily the parasite 

 inserts its egg into the egg of the host. The parasitized host larva, 



