288 



PRODUCTION OF RACES AND SPECIES IN LEPTINOTARSA. 



At the time this experiment was started, in May, 1901, beetles of the same 

 generation were taken and reared in cultures until May, 1902, and showed no 

 tendency to give, under normal conditions, extreme variations. In May, 1902, 

 these were subjected to two sets of conditions, one hot and dry, the other hot, 

 dry, and low pressure. These two lots will be considered separately. 



From the apparently pure stock, 7 males and 7 females were in May, 1902, 

 subjected during the first half of their reproductive period to hot, dry condi- 

 tions, during which time they laid 409 eggs. For the latter half of the repro- 

 ductive cycle they were kept in normal condition, laying 840 eggs. From the 

 409 eggs developed and laid in changed surroundings I obtained 64 adults, as 

 follows : 



(A 1) Normal (apparently) decemlineata, 12 males, 8 females; (A 2) L. 

 pallida, 10 males, 13 females; (A 3) L. immaculothora.v, 2 males, 3 females; 



.GENERATIONS 

 I 



4 1 X 4 9 ' Normal decemlineata subjected for % reproduction period 



r -__fto conditions of experiment; -/r to normal conditions. 



(A) 



IB) 



III 



IV 



B 



DECEMLINEATA 

 319 , ;gs 

 30 <J, 31 $ 



6<J, |6 



DECEMLINEATA 

 42,?, 50? 



I 6 ? 



DECEMLINEATA 

 20 S, 25 9 



DECEMLINEATA 

 48 S, 53 9 



killed 



DECEMLINEATA 

 500 egss 

 6rJ, 89 



1 



DECEMLINEATA 

 18 c?, 30 9 

 1<J. I 3? 



DECEMLINEATA 

 21 $, 26 9 



not continued 



1 



IMMACULOTHORAX 



2$ 



killed by disease. 



killed 



Text-figure 25 



PALLIDA 



40 <?, 42 9 



2<? X DECEMLINEATA 



HYBRIDS 

 16c?, 189 

 5 cT L8I 



PALLIDA DECEMLINEATA 

 6<?, 49 a"' 1 HYBRIDS 

 1<J I 29 16 o\ Lit? 



PALLIDA PALLIDA DECEMLINEATA 

 18cT,239 8c?, 79 and HYBRIDS 



killed 26 Si 28 9 



killed 



and (A 4) L. albida, 9 males, 7 females. These four lots were separated and 

 reared, with the exception of pallida. The 840 eggs laid in normal condi- 

 tions gave 123 normal decemlineata, and these I designated B. 



The Lots A 1 and B were reared side by side in the following generations 

 and both gave normal beetles as far as could be determined, but as the period 

 for hibernation approached, those of A 1, instead of going deep into the 

 ground, as did B and as is normal, activated on top or close to the top. The 

 Lot B went into hibernation in September, A 1 in late October and early 

 November. In January (January 2) Lot A 1 emerged from aestivation and 

 began breeding, giving a brood, part of which hibernated and part continued 

 breeding for five generations, then hibernated, and then emerged and bred 

 through five more generations. These hibernated again, and in the fourth 

 generation of the third cycle of five generations were killed in July, 1904. 

 These successive generations were all reared under exactly similar conditions, 



