xxxiii, '221 ENTOMOLOGICAL NEWS 263 



Ovipositional Habit of Pyraustomyia penitalis 

 Coq. (Dip., Tachinidae). 



By H. W. ALLEX, Agricultural College, Mississippi. 



Pyraustomyia (Panzcria) penitalis Coq.* is a common 

 Tachinid parasite of the smartweed borer. Pyrausta am si id 

 Hein. Adults of this parasite were abundant at Columbus, 

 Ohio, during the summer of 1921 and their method of ovi- 

 position was several times observed. To the author at least, 

 their rather unique method of spanning the distance from adult 

 fly to concealed host was new, and differed from the varied 

 methods of oviposition and larviposition previously noted. 



The smartweed borer infests the cane of one of the more 

 common smartweeds, (Polygonum pennsylvanicum} , entering 

 by a small hole at the node and developing within short tunnels 

 between the nodes, in its earlier instars in small colonies near 

 the tip, later as solitary larvae in the older succulent joints. 



Females of Pyraustomyia penitalis in the act of ovipositing 

 were observed to approach an infested node and quickly fasten 

 a minute maggot enclosed in a very thin sheath of chorion, 

 upon the cane, near the entrance hole of the borer. The 

 maggot in all cases emerged from the sheath at once. Some 

 found and entered the tunnel of the borer within a few 

 seconds, while other instances were observed where the young 

 maggot had been unable to find the entrance of the tunnel 20 

 minutes after oviposition. Maggots emerging from the 

 sheath moved at first on a straight line represented roughly by 

 a prolongation of the longitudinal axis of the sheath, then 

 failing to find the entrance hole of the borer would take a 

 wandering course, frequently raising the anterior end and 

 waving the head in the air. The course of the minute maggot 

 after entering the tunnel of the borer until it appeared within 

 the body of the host was not observed. Young maggots were 

 recovered from the blood of borers a few hours after ovi- 



* Several adults were sent to Mr. John Tothill who has recently been 

 \vorkiiiL' on a revision of this group of Tachinidae. He places Coquillett's 

 Panccria pcnitalis in the genus Pyraustomyia, Can. Ent., Vol. LIT I. 

 p. 201. 



