249 



PHYTODECTA VIMINALIS, A VIVIPAEOUS 

 BRITISH BEETLE. 



By C. B. Williams, B.A., F.E.S. 



On May 11th, 1913, adults and larvae of Phytodecta 

 (Gonioctena) viminalis were found in numbers on some sallow 

 bushes in the New Forest. A close search was made for eggs 

 but none were found, although quite young larvae, apparently 

 just hatched, were common. A female was then found which 

 seemed to be ovipositing, but on the leaf were only a group of 

 very small orange larvae, nor was there any trace of egg-shells, 

 though it was indicated from the uneaten condition of the leaf that 

 they had only just hatched. The latter observation in particular 

 suggested so strongly the possibility of viviparity that numbers 

 of the adults were brought back for closer examination. It was 

 then found that the surmise was correct, and females were 

 watched in captivity and were seen to lay small orange-coloured 

 larvae quite free of any shell or enveloping membrane. Further, 

 on dissection of females about to lay, many similar young larvae 

 were found quite free of any shell in the lower part of the ovary 

 and oviduct. 



Viviparity has been recorded in the allied genus Orina by 

 various writers ; in 0. vittigera, 0. cacalics, and 0. gloriosa by 

 Chapman and Champion (Trans. Ent. Soc. 1901, p. 1-7), in 

 0. siiperba and 0. speciosa by Perroud (Ann. Soc Linn, de Lyon, 

 1855, p. 402-8), and in 0. speciosa var. venusta by Bleuze 

 (Petites Nouvelles Entomol. October 1st, 1874, and Ent. Mo. Mag. 

 xi. 1874, p. 136), but so far as I am aware it has not been recorded 

 in the genus Phytodecta or in any British beetle. According to 

 Perroud 0. superba only lays one larva at a time at intervals of 

 about twelve hours, so that this species differs slightly from the 

 one under consideration. 



The only account of the life-history of Phytodecta viminalis 

 is by Cornelius in 1857 (Stett. Ent. Zeit. xviii. p. 165). In the 

 specimens he observed, however, eggs were laid which hatched 

 on the first day. He describes the eggs as reddish in colour 

 and cylindrical, slightly pointed at the ends. It would appear, 

 then, that the same species can, under different conditions, be 

 either viviparous or oviparous. 



The life-history of the beetle is as follows : — 



The adults emerge from hibernation towards the end of 

 April (three were found on April 19th, 1914). Both sexes are 

 very active in the sunshine, and in the early part of May pair 

 many times. They have a habit of sitting at the base of a leaf 

 with the head pressed right into the axil ; this has also been 

 observed in the allied South European species P. variabilis by 

 Bateson (Proc. Zool. Soc. Lond. 1895, p. 850). They fall to the 

 ground if disturbed. They eat readily the leaves of the rough 



ENTOM. — SEPTEMBEK, 1914. X 



