460 EXPERIMENT STATION EECOED. 



36° and minimum 4". Under artificial conditions offspring were reproduced 

 during a day of temperature 65° to 103°." 



The principal insect enemies of the green bug are syrphus flies, the aphis 

 lion, ladybird beetle, and the parasite LysipMebus tritici. Studies of L. 

 tritici are summarized as follows : " In laboratory experiments the maximum 

 number of green bugs parasitized by a single individual was 95; average num- 

 ber, 38 ; length of life in laboratory, 3 to 6 days ; minimum period of develop- 

 ment in laboratory, 7 days. The ratio of male to female parasites is 34 : 65. 

 Lysiphlebus is also parthenogenetic, the offspring being almost entirely com- 

 posed of males. Only one parasite develops in the body of the host. The 

 lowest temperature at which liysiphlebus was observed attempting to oviposit 

 was 35° F. The antennje of the female vary from 12 to 13 joints and of the 

 male from 14 to 15 joints. Five parthenogenetic males had 16-jointed antenuie. 

 In the laboratory breeding cages Lysiphlebus parasitized a small percentage of 

 M. granaria and would parasitize more freely Siphocoryne avence, but would 

 not parasitize M. trifoUi or 31. chrysanthcmicolen or Chaitophorus ncgundinis. 

 From field observation, however, it appears that Lysiphlebus does not per- 

 petuate itself and maintain a general distribution on these other hosts." 



The author concludes that the green bug distributes itself mox-e rapidly than 

 the parasite, succeeds in existing and increasing in unusual numbers free from 

 the pai'asite, and that parasites when transi)orted and introduced into areas 

 previously free from the parasite become active in the reduction of the green 

 bug. In view of these facts he considers the artificial distribution of the 

 parasite at such times to be a practical means for controlling the green bug. 



The review is by C. W. Woodworth of the California Station. 



The green bug- and its natural enemies, S. J. Hunter (Science, n. ser., 31 

 (1010), Xo. 788, pp. 190-192). — A reply to the review of the above article. 



The influence of climate upon the green bug and its parasite, P. A. Glenn 

 {Bui. Univ. Kans:., 9 {1909), No. 2, pp. 165-200, figs. iS).— The main factors, 

 chiefly climatic conditions, that enter in to regulate the abundance of the green 

 bug in this country have been studied and are discussed in connection with 

 temperature charts. 



The author flnds that the green bug can not endure the high temperatures 

 which prevail in summer, or the low temperatures which i)revail in winter In 

 most of the grain-growing sections. " For this reason it is confined to the 

 temperate zone, and chiefiy to those regions bordering on large bodies of water, 

 where the great extremes in summer and winter do not occur, rather than to 

 inland regions." 



The parasite of the green bug {Lysiphlebus trilici) becomes inactive when 

 the temperature falls below 35 or 36° F. and remains motionless on the blade 

 of wheat or on some other object " until the temperature falls to the minimum 

 limit of their endurance, which is about 17°, and then fall to the ground dead, 

 or until the temperature rises to 35° or above, when they become active again. 

 From 35 to 40° they are only feebly active, but have been observed to sting 

 bugs at 38 and 40° and to try in a very feeble way to sting bugs at 35° F., but 

 apparently without success. As the temperature rises above 45° F. their 

 activity increases, and appears to be about normal at 70°. At temperatures 

 higher than that they show a greater tendency to take flight and a less tendency 

 to seek for bugs for the purpose of stinging them. Their normal method of 

 passing the winter is in the pupa state, and they can probably survive very 

 severe winters. . . . From 61 experiments the following results were obtained : 

 The development period at 35° is from 114 to 140 days: from 55 to 60°, 23.4 

 days; from 60 to 65°, 16.06 days; from 65 to. 70°, 13.07 days; from 70 to 72°, 

 11 days. In these experiments the minimum time noted was 7 days." When 



