According to The Standard, Lacewings have been around for a little more than 50 years. They first appeared in country areas of Queensland in the early 1940's and were reported in the UK in 1948. Although classified as a rare variety, they are one of the few rare varieties that can be competitive with Normals, Opalines and Cinnamons when the major awards are decided on the show bench.
Lacewings are recognised by their red eyes, yellow or white body colour, pale violet cheek flash, Cinnamon spots, neutral tail quill and pale Cinnamon tail, together with clearly defined Cinnamon markings on their wings. It is the wing markings that give the variety its name. Suppression of melanin in the feather leads to the observed body colour - yellow in the greens and white in the blue series.
If we inter-cross Inos, Lacewings and Texas Clearbodies we get only Inos, Lacewings and Texas Clearbodies, not Normals, which you would expect if different genes were involved. This tells us that we are dealing with different but allelic mutations (ie, the same gene mutated in different ways) and/or variation due to composite phenotypes involving more than one gene, in this case, Cinnamon, a gene closely linked to Ino.
One plausible theory is that the Lacewing is a Cinnamon Ino (Cinnamon Lutino or Cinnamon albIno). If that is correct then Lacewings are the only composite variety on the matrix. To test this hypothesis, we could mate a Lacewing cock to a Cinnamon hen. All hens produced should be Lacewings and all cocks produced should be Cinnamons (split Lacewing). As I understand it, this is indeed what is observed for such a mating, proving that all Lacewing cocks are Cinnamon (as well as Ino). {I have not yet done this mating myself, so please let me know if this is not the case}. Had such matings produced a proportion of normal cocks, our hypothesis would have been rejected. An alternative hypothesis could have been that Lacewing was entirely due to another mutation of the same gene in which Ino, Texas Clearbody and Lacewing were an allelic series. However, from now on we will assume that the first hypothesis is the correct one.
Straight Forward Genetics
The genetics of Lacewings is straight forward as long as it is realised that although the phenotype depends upon expression of two genes, Ino and Cinnamon, the two genes involved are in very close proximity on the sex chromosome. Because of the closeness of these genes on the same chromosome (they are genetically very tightly linked), they are almost always inherited together. Thus, for practical reasons, breeders may consider them as one gene. (The linkage referred to here is much tighter than the linkage between the Yellowface and the dark factor).
An understanding of the genetic basis of the Lacewing phenotype has important implications for the selection of outcrosses: the outcross need not necessarily be a Cinnamon, as is often stated. Cinnamon and Ino need to be transmitted on the same chromosome homologue if we want to see Lacewings produced. In split Lacewing cocks, it is immaterial whether or not Cinnamon is on the other chromosome homologue, the homologue brought in from the outcross which does not carry Ino. Presence of Cinnamon on this other homologue, without Ino gives a cock, which is Cinnamon split Lacewing, rather than Normal split Lacewing. Absence of Cinnamon (i.e. normal) on the homologue not carrying Ino gives a cock, which is normal split Lacewing. Thus, split Lacewing means split Ino and split Cinnamon so long as the two genes are on the same homologue - to allow cotransmission to the next generation. The two types of splits referred to above, each mated to the same Lacewing hen, give the same expectation of 50% Lacewing chicks. It will not be possible to distinguish between those bred from the Cinnamon split Lacewing cock from those bred from the normal split Lacewing cock.
The most efficient use of an outcross can only be made in the combination Lacewing cock with normal or Cinnamon hen. (Opaline is not favoured if the breeder is intent on maximising the wing feature of this variety, although Opaline Lacewings should not attract any penalty on the show bench). The suggested pairing where the cock is Lacewing gives Lacewing hens and split Lacewing cocks in the first generation. The alternative combination, normal or Cinnamon cock with a Lacewing hen, gives split Lacewing cocks and normal or Cinnamon hens; there are no Lacewings produced from this outcross for two generations, thus improvement is much slower.
The same basic principle applies to any outcross for any variety: use the best bird you can get hold of. It needs to have exceptional head qualities, especially good frontal and width between the eyes, a deep mask, good shoulder, a smooth back-line and good size including substance behind the perch. Any large bird used needs to be balanced, with head qualities remaining in correct proportion to the body size, as depicted in the Standard. Few of us have such birds, so we just use the best that we are capable of producing. In addition, for yellow Lacewings, one might choose a dark factor bird to intensify colour, possibly at the expense of head qualities, which might drop off with the dark factor. For white Lacewings, you will choose a Cinnamon or normal grey in order to control the blue suffusion, a common fault in Lacewings.
If you breed both yellow and white Lacewings you would keep them in separate families because yellow and white Lacewings have different requirements for colour modifiers, as stated above. Introduction of grey into yellow Lacewings would have the same effect as it has on black-eyed yellows and Lutinos; it changes the yellow from buttercup to mustard. Hence, I wonder why some breeders advocate the use of grey greens as outcrosses for LutInos and yellow Lacewings as this certainly introduces the grey gene into the family. Similarly, if you use greys to improve your white Lacewings you would not want to cross your white Lacewings to your yellow Lacewings, for the same reason. Alternatively, if you use the dark factor to improve colour of your yellow Lacewings, you will not want to cross these with your whites Lacewings where the dark factor could increase the risk of pale blue body suffusion.
Another composite, the fallow Cinnamon, closely resembles the Lacewing. Lacewings have a neutral tail feather quill whereas Cinnamons and fallows have brown and dark brown tail quills respectively. So I wonder whether the colour of the tail quill could be used to distinguish between Lacewings and fallow Cinnamons?