70 



of this are seen in trifolii, tyan.talpina, and filijienclulae ; the first 

 named species has five spots, but local races have been found on the 

 Continent which develop a sixth spot. Trmisalpina commonly shows 

 two distinct forms with five and six spots, thus overlapping /z7/jj(?»(f»- 

 lae, which occasionally develops a five-spotted form ; when this 

 happens in some of the smaller races they are very difficult to differ- 

 entiate, although the brighter colour, and generally the position of 

 the spots, allows one, after experience, to separate them with some 

 degree of confidence. The same difficulty is shown in certam races 

 of jnirpitralis and achilleae, especially in some of the forms from Asia 

 Minor. In regard to confluence, it is curious that some species are 

 particularly prone to this form of variation, as in the British species, 

 trifolii and loniccrae ; although undoubtedly very closely related, 

 trifolii regularly produces confluent aberrations, and it is almost 

 impossible to collect this species in any locality without getting this 

 form ; in some seasons it is so abundant that at least 50% show con- 

 fluence in some degree, whereas with hmicerae confluence is of the 

 greatest rarity, even such a minor form as the coalescence of spots 

 3 and 4 is difficult to obtain. 



Teratological forms are abundant iu this genus, examples having 

 one or more wings reduced in size, or with the wings of unusual 

 shape being especially frequent. Rarer divergent forms, such as an 

 extra leg or wing, have been obtained. Dr. Chapman reported 

 having taken a female e.vnlans with extra wings ; and Christ\% trifolii 

 (see "Entomologist," vol. 27, p. 258) with what may be described 

 as three forewings and no hindwings. The absence of one or more 

 wings is of frequent occurrence ; and several instances have been 

 recorded of imagines being taken with larval heads. This prevalence 

 of congenital aberrations may perhaps be accounted for in a simple 

 manner. The tenacity of life in the Zygaenas is well known, and 

 the pupa being very soft, and without any great measure of protec- 

 tion from the cocoon, it is liable to sustain injuries that in many 

 other species would prove fatal. In Zygaena the accidental crush- 

 ing would not cause death, but some malformation would result. A 

 pupa that has met with a casualty of this nature nearlj' always pro- 

 duces an imago with dark green or blue of the forewings changed to 

 a slatey colour; this may be local, or may cover a considerable area. 

 A pin prick on the wing cases of the pupa will produce an imago 

 with a small round hole in the wing surrounded by this slatey blue 

 colour. 



As an example of the vitality of this genus, it is possible to open 

 a pupa and extract the imago some time before it is due to emerge, 

 and the msect will continue to live, but of course will not expand 

 its wings or in any way develop. A female so treated will attract 

 males, although I have never been successful in obtaining a pairing 

 with examples so treated. This tenacity of life is conspicuous 

 through the whole life-cycle, with perhaps the exception of the ova 



