DIMORPHA VERSICOLORA. 259 



very large and active Tachina larva, which, therefore, had not hindered 

 the development of the moth. 



Habits. — The males are the first to emerge, a few sunny days 

 sufficing to bring them out; the females soon follow, both sexes almost 

 always appearing before or about noon. The females (at least in 

 captivity) " call " at intervals, both during the day and evening ; at 

 times they will cease simultaneously, and the restless, impetuous males 

 then immediately settle down as though some mysterious influence 

 had passed over them; on the "calling" being renewed, the males 

 wake up and resume their impetuous career until union is effected, and 

 when a male disappears beneath the shadow of the wing of the 

 much larger females, one knows that one is in a fair way to secure 

 fertilised eggs. Those who are desirous of obtaining perfect speci- 

 mens bred in confinement should place $ s, in the act of "calling," 

 on upright stems about the thickness of a quill, and although the 

 removal will momentarily stop the "calling," it will quickly be renewed. 

 The duration of union varies from 6 — 30 hours ; in one case, after 

 a pairing of not more than ten minutes, only the first 5 eggs laid 

 were fertile. In a normal batch, barren eggs generally lie side by 

 side, having followed each other from the ? , and it would appear that, 

 for the moment, the fertilising fluid had ceased to perform its function, 

 but quickly to have resumed doing so again (Gascoyne). Butler 

 notes (Ent. Rec, xiii., p. 328) that he placed two 2 s on a birch 

 bush, at 3.15 p.m., April 17th, 1901. One commenced to "call" at 

 once, and in 10 minutes a $ that came up against the wind was 

 paired with her; the other 5 did not commence to "call" until 4.50 

 p.m., when another $ came up and paired directly. The $ s were 

 placed next morning with fresh females and both paired again in 

 less than 15 minutes. The males, when at rest, hold their antenna, 

 half extended in front, almost as do those of Lasiocampa querciis. 

 Emergence usually take place in the morning from 8 a.m., 

 but sometimes much later — 1 p.m., etc. Pairing generally takes 

 place in the morning, or early afternoon, and the moths usually 

 continue paired until nearly dusk, when egglaying almost immediately 

 commences. On one occasion a male paired with a female at 2 p.m. 

 (March 31st, 1859), and these did not separate until 7 p.m. on April 

 1st, the copulation lasting for 29 hours. A male will pair with more 

 than one $ . On March 24th, 1859, a pairing took place between 

 a $ and $ , and on the next day the same male paired with another 

 female, both laying full batches of fertile eggs. The females 

 appear to begin to " call " about three hours after their emergence 

 from pupa, and quickly pair if a $ be available ; if none, they 

 continue to " call " until considerably after 4 p.m. if the weather 

 be sufficiently warm. A male that emerged on April 4th, 1859, paired 

 on that date with a female that emerged on March 28th, without 

 hesitation, at about 1 p.m. (Merrifield). Bernard-Smith also observes 

 that the moths often pair more than once with evident advantage 

 to the fertility of the ova. Alderson observes that a $ and $ he 

 had, paired about 12 noon on March 10th, 1891, remained in copula 

 till 6 p.m., after which the ? laid 1 20 ova. We have obtained large num- 

 bers o; pairings at various times, all, however, before 5 p.m., the copula- 

 tion frequently lasting until 8.30 p.m. or 10 p.m. A moderately high 

 temperature is necessary for pairing to take place, and Tugwell 



