December, '09] JOURNAL OF ECONOMIC ENTOMOLOGY 895 



oval, flat, green patches, each containing an average of about 117 

 eggs, as shown below. 



Number of eggs: 10-20. 25-50. 75-100. 100-150. 150-200. 275. 300. 360. 

 Number of masses: 7. 6. 5. 3. 4. 2. 3. 1. 



The table shows plainly the great variance in the number of eggs 

 in one mass, ranging as it does from a very few to over 300. A 

 weighted average of the above gives 117 eggs as the average number 

 laid at one time. 



The total number of eggs produced by one pair of moths is an 

 interesting as well as an important feature. For this purpose, single 

 pairs of moths which had just emerged, were isolated and placed in 

 glass cylinders containing fresh rose twigs. As soon as the eggs were 

 noted they were removed and counted. The results were as follows: 



Number of eggs laid by individual females: 650, 488, 80, 375, 52, 83, 200, 

 575, 190, 45, 400, 575. 



Averaging the above gives 305 eggs to be the average number laid 

 by one female moth at room temperature having a mean of 70°F, 

 The masses vary considerably in size, four millimeters being a good 

 average width. The eggs are glued together by gelatinous material 

 and often overlap. From our observations in the infested green- 

 house and in the insectary they are generally deposited on the older 

 leaves of the plant rather than on the fresh shoots. The egg mass is 

 usually a shade lighter than the green leaf. Oviposition usually 

 takes place at night, although cases have been observed on very cloudy 

 days. Practically all the eggs of a mass hatch at once, leaving the 

 empty shells of the mass whitish in appearance. In case of parasitism 

 the individual eggs are blackened by the pupa of the parasite. The 

 figure in Plate 17 above E is a parasitized egg mass, while the light 

 miasses are unparasitized. 



The time of incubation varies considerably according to the tem- 

 perature. A number of freshly deposited egg masses were put in 

 vials and placed in an incubator kept at 80°F. The length of the 

 egg, larval, and pupal stages were all determined with specimens kept 

 in a glassfront incubator kept constantly at 80°F., which is practically 

 the mean temperature of the rose house in summer. Observations 

 were made every morning from which were obtained the following 

 data: 



Number days' incubation 5 6 7 8 9 



Number of egg masses 10 12 11 9 4 



From the above experiment 6.67 days is found to be the average 



