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Journal of the Lepidopterists' Society
SEASONAL FORMS OF ANTHOCHARIS SARA (PIERIDAE)
William H. Evans 3333 Wisconsin Avenue, NW, Washington, D.C. 20016
Interesting field observations by Fred Thorne of an unusually early appearance of the summer form of Anthocharis sara Lucas on 14 March 1973 in wild populations near San Diego, California are worthy of immediate publication. His request for data on my rearing of summer form "sara" from ova laid by spring form "reakirtii" points out how important it is for this information to emerge from the seclusion of my entomological notebooks. These 1953-1956 rearing records are not outdated—after all, in their recent book, Emmel & Emmel (1973) cite my 21 year old paper (Evans, 1952b) as evidence of the short pupal period of summer form "sara." That report referred to a 1941 emergence.
Using method I of Masters (1972), I designate these seasonal forms as:
Anthocharis sara Lucas form "sara" (summer brood). Anthocharis sara Lucas form "reakirtii" (spring brood).
It might have been better if a name other than the specific name had been given to the summer form; however, sara apparently has always referred to this large form with a lightly speckled under side.
Twenty years of studying, collecting and rearing members of a wild population of A. sara in La Tuna Canyon, elev. 1,200 ft., Verdugo Mts., Los Angeles County, Calif, where my backyard was one of the main orange-tip fly ways (Evans, 1952a, 1955), proved to me that this species did not have a standard spring and summer brood set-up. Specimens of summer form "sara" are produced from that small portion of the offspring of a female "reakirtii" which spend only two to three weeks in the pupal stage, while other siblings will emerge as spring form "reakirtii" after remaining as pupae until the next spring, or even the second or third spring. Flying in springtime with these "reakirtii" offspring of "reakirtii" will be "reakirtii" from a second source—ova laid by summer form "sara" during April, May or June of any of the three preceding years. Differing weather conditions cause variations in time and duration of flight periods from year to year. If spring rainfall ceases too soon after the "reakirtii" flight, summer form "sara" will not even appear that year. If several rainless weeks during late March and early April are followed by soaking rains in late April and early May, a brood of summer form "sara" will emerge the last part of May and the first week of June.
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At this point, rearing data which influenced my opinions should be given. The total number of specimens reared can be listed under four categories:
la. Spring form "reakirtii" which are the Fi generation of "reakirtii" females, and which emerge first, second or third spring after pupation. 1950-1959, 350 reared from ova laid by 25 females (some wild, others emerging and mating in rearing cages).
lb. Summer form "sara" which are Fi of "reakirtii" females, and which emerge 16-21 days after pupation. 1955, one male 27 May. 1956, one female 6 May.
2a. Spring form "reakirtii" which are Ft of summer form "sara," and which emerge first, second, or third spring after pupation. 1952-1956, 28 specimens from ova of 8 wild "sara" females.
2b. One male of intermediate maculation emerged 15 March 1953 as Fi of a wild "sara" female after 9 months as a pupa. The under side of the hind wing of this male has a "sara" pattern with gray specks of very small size and also fewer in number than in "reakirtii," while the hind wing upper side has the marginal black spots at the ends of the veins almost as large as in "reakirtii."
The first three categories enumerated above can be explained logically. The one example under listing 2b adds confusion to the whole situation, especially with a sister of this "sara"-like male emerging the following day as a genuine spring form of "reakirtii." Many offspring of summer brood "sara" should be reared to see if more of these pseudo-"sara" would occur. No wild specimens of this sort were ever found.
In an attempt to produce summer form "sara," special rearing methods were tried with larvae whose parents, both spring form "reakirtii," had mated for 30 minutes in the rearing cage on 27 March 1955. The mother was the offspring of a wild yellow female "reakirtii" collected 3 February 1953. The father was offspring of a yellowish "reakirtii" female # 13 caught 25 February 1954. Larvae were placed in white organdy cylinders 3.5 cm in diameter and 7.5 cm long with a circle of the cloth sewed in one end and a thread drawstring attached for closing the opposite end tightly around a stem of foodplant. Each mini-sleeve, with one 4th instar larva inside, was tied around one or two flowering spikes of sweet alyssum, Lobularia maritima (L.) Desv. The plants were growing next to the top of a rock and cement wall along the border of a flower bed. In 1955, the spring rains seemed to be over in early March, but 41 days later rain fell steadily for 13 hours on 21 April. The larvae were installed in the sleeves in time to receive 3 hours of rain on 26 April, 13 hours on
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Journal of the Lepidopterists' Society
30 April, and 4 hours on 1 May. Some larvae were in prepupal stage during 11 hours of rain on 7 May—one of these produced a male of summer form "sara" on 27 May. Members of the wild population emerged simultaneously, a fresh male being caught each day on 26, 27, 28 and 29 May. The confined larvae probably grew more slowly than the wild ones, which could have matured from ova of wild "reakirtii" laid as late as 17 April when the last female of the spring form was seen that year. In addition to the four May males, only two other wild "sara" were seen in 1955: one male and one female on 19 April.
Larvae in sleeves were established on the plants again in 1956 when 38 hours of rain during four April days followed a rainless March. A female of form "sara" emerged 6 May, the same day that a yellow wild female flew through the yard. For the entire "sara" season (22 April to 5 June), 5 wild males and 5 wild females were observed or captured. Between 7 May and 18 May and again between 20 May and 4 June there were gaps in the flight period.
In both 1955 and 1956, the occurrence of a second period of spring rainfall caused the emergence of a small number of summer form "sara" in the wild population as well as among reared individuals exposed to the rainfall. Many pupae of the wild population must have initiated diapause to await springtime emergence as form "reakirtii," which is what occurred with twelve pupae in organdy sleeves—four of these which were brothers or sisters of the reared male "sara" emerged as "reakirtii" in February and March 1956.
In southern California, rains in April and May are considered unusual; in almost six out of ten years, there is no rain after the end of March. Several recent years have also been short of rainfall in fall and winter. In contrast, early 1973 was unusually wet in San Diego County as reported in letters from Fred Thorne, with frequent long periods of steady rainfall in January, February and March.
During the few sunny days in late January, throughout February, and in early March, Thorne found a few Anthocharis sara spring form "reakirtii" flying at several locations. Then came a big surprise on 14 and 15 March when he captured a female and male of summer form "sara"—the first March appearance of this form during his many years as a lepidopterist! At four different localities near San Diego during the last half of March 1973, he found a total of eight specimens of the summer form. At Lower Otay Lake, where a male "sara" was flying 15 March, no more were seen in late March or the first week of April; however, on 12 April, Thorne found summer form "sara" flying all over the area and collected 21 males and 5 females. Thome's observations on the earliest
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"sara" specimens seems to indicate a maturation period of five or six weeks from oviposition by spring form "reakirtii" to emergence.
Conclusions
Two factors prove that the production of summer form "sara" is actually triggered during the larval stage: (1) The reared male received rainfall during the last two larval instars but none as a pupa. (2) Because size of adults is determined by size of pupae, the large size of wild "sara" adults indicates that larger growth occurred in the larval stage thus resulting in larger pupae.
Genetically identical larvae respond differently to the same conditions of rain and sunshine—from the same batch of ova, some larvae transform into short duration "sara"-producing pupae, while others form diapausing "reakirtii"-producing pupae. Perhaps micro-climatic conditions are a factor—during rainy periods, the larva on top of a stem gets wetter than one clinging to the under side of a stem. Differing temperatures between shady and sunny side of a stem on clear days might have an influence.
In an earlier paper (Evans, 1952b) the possibility was considered of two different kinds of form "reakirtii" which could be distinguished by the amount of yellow on the apex of the forewing under side. Additional rearing since then proved this to have no diagnostic value. The possibility of two genetic strains of the species sara, one of which never produces summer form "sara," cannot be dismissed.
It is hoped that this paper will arouse interest of many lepidopterists in rearing Anthocharis sara to help clarify various problems.
Most of my Anthocharis specimens are now in the Allyn Museum of Entomology. The reared "sara" male and a few "reakirtii" are in the Yale University collection.
Literature Cited
dos Passos, C. F. 1964. A synonymic list of the Nearctic Rhopalocera. Mem. Lep.
Soc. 1: 1-145. Emmel, T. C. & J. F. Emmel. 1973. The butterflies of Southern California. Nat.
Hist. Mus. Los Angeles Co. Sci. Ser. 26: 1-148. Evans, W. H. 1952a. Luring Anthocharis sara into the net. 1. Lepid. Soc. (News)
6: 100. ----------. 1952b. Notes on Anthocharis sara and reakirtii. J. Lepid. Soc. (News)
6: 106. ----------. 1955. Retrieving marked Anthocaris reakirtii. J. Lepid. Soc. (News)
9: 118. Masters, J. H. 1972. A proposal for the universal treatment of infrasubspecific
variation by lepidopterists. J. Lepid. Soc. 26: 242-260.