264 ENTOMOLOGICAL NE\VS [Nov., '22 



position, indicating that soon after entering the tunnel, maggots 

 find their host and penetrate its body. 



This manner of effecting parasitism seems remarkable in 

 several respects. The host, though a borer and secure during 

 most of its existence from the direct attack of a Tachinicl 

 parasite, is highly vulnerable to this specialized method of 

 approach, as is indicated by the frequent high rate of para- 

 sitism. When the borer changes from the gregarious to 

 solitary life, it leaves the colony tunnel and crawls on the out- 

 side of the cane to a joint lower down, cutting a new entrance 

 there, and at this period of its existence is particularly vul- 

 nerable to direct parasite attack. But so far as observed, this 

 parasite takes no interest in exposed larvae. Maggots, as 

 indicated by the cast sheaths, are habitually deposited at dis- 

 tances ranging from about one-fourth inch to over an inch 

 from the borer entrance. Before the parasitic life of the 

 maggot could begin, it was forced to perform the tortuous 

 and difficult journey from the point of oviposition to the en- 

 trance hole and then up the tunnel to the host and finally to 

 penetrate the body of the host. So far as observed maggots 

 were invariably placed near infested nodes. Superparasitism 

 was common, several maggot sheaths being commonly found 

 about the entrance containing but one borer. Many borers 

 were found to contain two and three maggots. Females were 

 induced to oviposit freely in small cages when confined 

 with infested canes. 



A Peculiar Damselfly Nymph of the Subfamily 

 Thorinae (Odon., Agrionidae). 



By JAMES G. NEEDHAM, Cornell University, Ithaca, New York. 



Among the aquatic insects collected by Dr. J. C. Bradley 

 on the Cornell Entomological Expedition of 1919-20 to South 

 America, there was one damselfly nymph of form so peculiar 

 I deem it worthy of special notice. When I first saw the speci- 

 men in a vial of alcohol I thought that a bur or spiny seed of 

 some kind was stuck to its tail, but when I got at the specimen 

 and undertook to remove the supposed bur I found it to be 



