Dec, '12] RUSSELL AND JOHNSTON: BIOLOGY OF TETRASTICHUS 431 



plants were large and the eggs scattered widely throughout the fields, 

 SO that the parasite had also scattered and was very hard to find. A 

 number of the parasites were collected, however, and taken into the 

 laboratory by the junior author and confined in vials with eggs of the 

 asparagus beetle. When the parasites had oviposited in them these 

 eggs were removed and the sprigs of the plant bearing them were put 

 in moist earth until the larvae of the beetle hatched. These larvse 

 were carefully supplied with fresh food from time to time and when 

 full grown were allowed to pupate in the bottom of the vials in soil 

 provided for that purpose. Many formed their pupal cells along the 

 sides of the vials and could be observed from time to time without 

 being disturbed. 



A few days after going into the soil the beetle larvse began to change 

 to pupse and still later numbers of them were observed from which the 

 parasitic larvse had emerged. 



The larva of Tetrastichus asparagi when mature is from 2 to 2.5 

 mm. long and 1 mm. wide; it is ovate and widest near the head, which 

 is bent under the body. The color is white, with the alimentary canal 

 appearing greenish. The surface is smooth and shining and devoid of 

 hairs. There are no legs and the larva seems to be incapable of motion 

 except to move the end of the abdomen around when disturbed. In 

 a few days after destroying the host, the parasitic larva changes to 

 the pupa. 



The pupa of this insect is about 1.5 mm. long and 0.5 mm. wide 

 and is yellowish white in color. It is convex dorsally with the head 

 bent under and the inconspicuous wing pads are folded along the 

 side, while the antennse and legs are folded under ventrally. The 

 head, thorax and abdomen are distinctly differentiated from each 

 other, the abdomen tapering posteriorly. During the latter part of 

 the pupal period, the pupa darkens considerably and just before 

 emergence is nearly black, with the eyes bright red. From 7 to 11 

 days were spent in the pupal stage and as the adults emerged from the 

 ground in from 24 to 36 days after the host eggs were parasitized, the 

 egg and larval stages together required 17 to 25 days. 



The living adult of this insect has the head and thorax bluish green, 

 and the abdomen green with coppery iridescence. The antennse are 

 black and the eyes dark red Avhile the wings are hyaline ^^dth black 

 venation. The legs are black, except tips of femur, tibia and tarsi 

 which are orange-yellow. The head is transverse and the abdomen 

 well rounded and ovoid. This insect is variable in size ranging from 

 a,bout 1.5 to 2 mm. in length. 



As soon as the adults emerged from the pupse they began an 



