A. GLENN RICHARDS 



157 



pretreatment conditions, percentages on the vertical axis represent hatching 

 under these conditions and subsequent survival under a favorable tem- 

 perature. Note that, for incubation at the above threshold temperature of 

 17°, they obtained an excellent hatch (85%) but even though the larvae 

 were immediately placed at 25° the bugs all died. In the author's laboratory 

 variable but relatively low survival values have been obtained (table 4) . 

 Whether this difference between their results and ours is related to dif- 



I I 7o Hatching 

 MM 7o to 2""" Instar 

 ^H % to Adult 



75 % R H, 



INCUBATION CONDITIONS 



Fig. 9. Bar diagram giving hatching percentages of Oncopeltus eggs under stated 

 incubation conditions, and percentages of those hatching that subsecjuently matured 

 under standard favorable conditions of 25°C and 50% R. H. After Hodson and Al 

 Rawj', 5. 



ferent humidities or to some other factor remains to be determined but 

 both sets of data show much lower than normal survival. 



Our attempts to determine the nature of this debility induced by a low 

 temperature that does not necessarily impede hatching have been largely 

 negative to date. Thus, there is no significant difference between the oxygen 

 consumption of recently hatched larvae from eggs incubated at 17° and 25° 

 (fig. 10 (. On a per larva basis the 25° individuals give slightly higher 

 oxygen consumptions; on a weight basis they give slightly lower ones. 

 There may still be a difference in oxidative metabolism because preliminary 

 determinations of the succinoxidase activity of brei (with exogenous suc- 

 cinate and cytochrome c) suggests a 2x greater activity from eggs incu- 

 bated at 25°C. Further study of this is needed. 



