63 



Such fact.s as these show that the various color types may develop 

 among bollworms grown as nearly as possible under similar conditions, 

 and suggest that the matter is entirely an hereditar^^ one. Neverthe- 

 less the apparent predominance of certain types on various plants and 

 under different conditions led us to undertake some experiments along 

 this line. Six lots of ten larvsB and one of three were fed on cotton, 

 tobacco buds, tomato buds, Irish potatoes, flowers and buds of cow- 

 peas, corn silk, and the leaves and spikes of Ama7'antiis spm.ostis^ 

 respectively, but variations peculiar to each lot did not appear. The 

 experiment was later repeated with twent}^ larvae from eggs of a single 

 moth, fed on cotton, tomato, potato, and tobacco, but afforded no fur- 

 ther results. Other experiments were tried by rearing larvae in moist 

 and dry atmosphere, and in light or dark situations, but no evidence 

 was secured. Cold weather influences to some extent the color of the 

 head. Normally this is black in the first stage and pale in the others, 

 but in the spring and fall and in the ice box, the black color persisted 

 through the second stage. 



In the field numerous variations, presumably due to environment 

 were noted. Among larvae feeding on cotton, the pale pink or green 

 type is apt to predominate, except when feeding on the foliage, when 

 bright greens and yellow make their appearance. On corn all three 

 types occur at nearly all times, although green individuals with crim- 

 son spots are rather scarce in midsummer. On alfalfa a uniform green 

 t} pe is most common. These dark greens, noticed in specimens feed- 

 ing on foliage, may be due in great part to the bright-green color of 

 the blood under such conditions. 



DURATION OF LARVAL INSTARS. 



This question was worked out very thoroughly by Mr. Girault in 

 the laborator}^ at Paris during the season of 1904. Some thirty lots 

 were reared with this object in view and the molts recorded as accu- 

 rately as possible down to hours. The number is too large to represent 

 consecutive generations, and the life C3^cles of the different lots overlap 

 one another more or less. The following table summarizes the entire 

 number: 



22051— No. 50—05 5 



