53 THE ENTOMOLOGIST. 



back is divided by a silvery-white thread-like line. There is a 

 thin medic-dorsal silvery-white line, and a similar line (subdorsal) 

 along each side. Below each subdorsal line is a stripe of the 

 same colour. The Geometer method of progression is now 

 changed for that of the Noctua. 



4th. — Head light pea-green. Dorsal area pea-green and 

 mottled with white. Each segment is divided by a well-defined 

 yellowish line. Under surface pea-green, but a shade darker 

 than the dorsal area ; legs and claspers same shade as the under 

 surface. On the back of each segment are two oblique pea-green 

 marks, which, in the next stage, meet like the arms of the 

 letter V- In this stage, however, they are not joined, but show 

 a disposition to converge on each anal division. There is an 

 interrupted medio-dorsal white stripe. On each side is a well- 

 defined silvery-white line, immediately bordering on which, above, 

 is a line of dark green. 



Last stage. — The caterpillar is uniformly apple-green, viz., a 

 shade darker than pea-green ; all the segments above and below 

 being beautifully mottled with deep yellow. The segments — 

 especially the 5th, 6th, 7th, 9th, 10th, 1 1th, and 12th — are well 

 divided by a line of this broom-yellow colour. Head yellowish- 

 green. Legs, claspers, and under surface the same mottled green 

 as above. The green oblique marks referred to in the preceding 

 stage meet on the centre of the anal division of each segment in 

 a Vj each arm of the V being slightly curved outwards, and then 

 inwards, before meeting. An interrupted, white, medio-dorsal 

 line runs along the back of each segment, beginning with the 

 2nd and intersecting the angles of the V-shaped marks. The 

 caterpillar is further ornamented by a supra-spiracular dark green 

 line along each side, bordered below by a silvery-white line, 

 especially distinct on the 2nd, 3rd, 4th, and 5th segments. In 

 the last stages there are two or three short, dark, and scattered 

 hairs emitted from the dorsal area of each segment. 



Pupation begins about the 20th of June. My notes show 

 that all my larvae had disappeared in the soil by the second week 

 in July. The moths appeared early in the following March : my 

 diary for 1890 gives the time between the 6th and 22nd, In the 

 Chester district, owing to the cold weather last spring, I did not 

 find the sallows in bloom before the 15th, and even then only in 

 sheltered places. Some allowance must therefore be made for 

 the early emergence of the bred insect, as " it appears ivith the 

 sallows, three or four days after they come out ; the same tem- 

 perature produces both " (Dr. Chapman). 



It will be seen that P. leucographa remains in the pupal state 

 about eight months. To keep pupae for that length of time in a 

 healthy condition is not a very easy matter, and it occurred to me 

 that as close an imitation as possible of natural conditions would 

 be most likely to lead to success. I placed the pots on a brick 



