346 



THE STUDY OF INSECTS 



Family Braconid^; 



The Braconids 



The family Braconida? includes a large number of species, which are 

 small or of moderate size. In this and in the following family the costal 

 cell of the fore wings has been eliminated by the coalescence of veins 



Fig. 583. — Wings of a braconid. 



(Fig. 583) and the venter is membranous and has in dried specimens a 



longitudinal fold. 



It is nof an uncommon thing, especially in vineyards to find a feeble 



caterpillar with its back covered with lit- 

 tle, white, oblong bodies, which the unin- 

 formed usually think are eggs (Fig. 584). 

 These are the cocoons of braconid parasites. 

 The larvae obtain their growth within the 



584. — Caterpillar with cocoons . B , . , - . 



of a braconid. body of the caterpillar, and just before it 



perishes they leave it, and spin their silken cocoons upon 

 its back. When these cocoons are examined with a lens 

 they are found to be beautiful objects, resembling in mini- 

 ature those of the silkworm. The adult parasite in em- 

 erging from its cocoon cuts a neat little lid at its upper 

 end. These parasites belong to the genus Microgaster. 

 Bunches of white or yellow cocoons of Microgaster are often 

 found attached to grass or other plants instead of to the 

 back of the caterpillar which the larvae have destroved 

 (Fig. 585)- 



Perhaps the most interesting of the com- 

 mon forms belonging to this family are 

 those belonging to the genus Aphidius. The 

 members of this genus are minute creatures 

 which infest plant-lice. If colonies of 

 aphids be examined, the dried bodies of 

 dead ones may be found in which the 

 abdomen is more or less spherical, being greatly distended. These bodies 

 remain clinging to the leaves in the position in which the insects were 

 when they died. From each one there emerges in due time an Aphidius. 

 The parasite in emerging cuts a very regular circular lid in the dorsal 

 wall of the abdomen of its host (Fig. 586). We have watched with much 



Fig. sS6. 



Fig. 58s. 



