G. H. FuKD . 113 



Wireworuis with, their tough highly chitiuised skins, and under- 

 ground habits, are almost free from internal parasites. Curtis (6), 

 however, says that wireworms have a Hymenopterous parasite and 

 quotes Bierkander as having found them. Forbes {I8th Repl. Stale Ent. 

 p. 47, 1891 — 2) records a parasitic fly as having been reared from a wire- 

 worm. Out of over 300 larvae collected, not one attacked by an internal 

 parasite has been seen. Graf found the same result with 10,000 larvae of 

 Limonius californicus. In this connection, I am informed by Mr FryeT 

 that he has not infrequently found wireworms parasitised by what is 

 probably a Proctotripid, at all events a Hymenopteron, but has never 

 succeeded in breeding it out. No bacterial or fungoid disease was 

 seen in any of the larvae in the field, or in the laboratory. In this 

 connection, Graf reports as having occasionally observed fungoid 

 attack in the field, but says that one fungus and two bacterial diseases 

 were common under laboratory conditions. He also says that one 

 bacterial disease was very fatal to the young wireworms, while the 

 older stages seemed to be immune. 



According to Leaflet number 10 of the Board of Agriculture (1916), 

 wireworms are parasitised by a species of the fungus Isaria. 



The pupae are difficult to rear; any disturbance or any slight 

 variation in humidity or temperature, was sufficient to cause them to 

 perish, and from the same causes some pupae passed into the perfect 

 state but failed to mature. No disease of any kind was noticed. 

 Graf notes that a few pupae of Limonius californicus were killed by a 

 fungus. 



Graf records a fungoid disease as having caused the death of adult 

 Elaters under natural conditions. 



Wireworms seem to be little affected by physical agencies under 

 experimental conditions. They were found to be little aft'ected by 

 excess of moisture, but they could not resist dryness and were killed 

 by frost. Under natural conditions it is probable that these factors 

 are of no importance, as tlie larvae can always burrow down deeper 

 in the soil, out of the way of frost, or in the search of greater humidity. 



8. SUMMAKY OF GENERAL CONCLUSIONS. 



1. This paper contains an account of the larval and pupal stages 

 of the Elater, Agriotes obscurus, whose larvae, together with certain 

 other related larvae, are known as "wireworms." 



