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Thread: Three-spot grass yellow?

  1. #1
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    Default Three-spot grass yellow?

    In a patch of vegetation where many comman grass yellow butts are flying around, found this different looking grass yellow. It has three cell spots on the forewing underside. By the key given in C&P4, this then must be the 3-spot grass yellow. But the shape of upperside borders and the brown apical patch cast doubts on this. Any suggestions?

    Horace
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  2. #2
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    Appear to be a rather small yellow relative to the flower ...

    Cannot be a E. blanda snelleni (3-spot grass yellow) , can make out the upperside forewing black apical border is serrated and quite deeply excavated at space 3 & 4 .

    if only we have an upper wing shot ..... to confirm that is the Eurema ada iona that we are looking out for

    from C&P4 :

    E. ada (14-18mm)

    Upperside forewing black border below vein 2 cut away towards the dorsum . Forewing apex rounded. Upperside pale greenish yellow. Forewing usually less than 18 mm.
    Sunny

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  3. #3
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    Thanks Sunny for the interesting ID suggestion of E. ada iona.
    According to C&P4, E. ada iona has only two cell spots rather than three.
    However my poorly taken shots of another two specimens (all very skittish, even in the cold wet weather) did reveal only two obvious cell spots, with the lowest one possibly hidden by the hindwing.

    My impression of the butts is that they are about the same size as the other common grass yellows, and not the small size suggested in C&P4.

    Horace

  4. #4
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    I suppose the wet, wet weather is encouraging Horace to shoot whatever comes his way. Even if they're these common yellow butts.

    And yes, E. ada has only two cell spots. E. blanda is the only species with 3 cell spots. This is described clearly in my Eurema spp. ID key posted earlier.

    It's a female Three Spot Grass Yellow that you've shot. Unfortunately, C&P4 does not feature the female of the species, leading to the belief that the females have the very thin black wing margin as the male pictured in C&P4. The females have thicker borders, with the deeply excavated border in space 3 & 4 like the other Yellows.

    The apical patch appears variably in this species, and a few of the others, so as an ID characteristic, it is not reliable to use this apical patch. Interestingly, both the Indian and Hong Kong books feature some of the Common Grass Yellows in different forms where the apical patch is featured on one of the "forms". Perhaps this phenomenon also applies to the Malaysian/Singaporean species, but not well researched.

    Here are some shots of the Three Spots during a period when they were plentiful at TBHP. In the mating pair, the female shows the thicker black wing borders, as well as some markings on the apical area of the forewings.
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    Khew SK
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  5. #5
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    Thanks Khew for the detailed description/illustration of the ID characteristics of the three-spot GY, especially for the female. This dispels all doubts about the ID of these GYs I encountered.

    Well in this wet weather, GYs are just about the only butts still actively flying around even in light drizzle, although I also sighted lime butt. and cycad blue which were easier targets than usual due to the cooler temperature.

    Horace
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  6. #6
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    Went to the same patch of vegetation again, and managed to obtain a shot of a mating pair of three spot GY with both butts showing the three spots (pic 1). There were many puddling males (pic 2). Also spotted a few GYs about half the typical size, but a closer scrutiny of the apical border confirmed they are just the usual common GY, and not the E. ada iona.

    Horace
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