JUL 20 191? 



NOTES ON TRIFURCULA IMMUNDELLA, ZELLER. 117 



Notes on the ovum and larva of Trifurcula immundella, Zeller. 



By ALFEED SIGH, F.E.S. 



Of the small genus, Trifurcula, we have three species in Britain. 

 The slight experience I have had of T. atrifrontella leads me to believe 

 that it may be attached to the oak, and in a letter, received some years 

 ago, from Mr. E. E. Bankes, the same opinion was expressed. T. 

 immundella, in the larval state, does mine imder the bark of Cytuus 

 scn/iarius, and the food plant of T. pallidella, the remaining species is, 

 in all probability. Genista tinctoria. I have delayed publication of my 

 note on T. iuiuuindella in the hopes that I might have been able to 

 complete the account of its life- cycle. Perhaps some other observer 

 will have the opportunity of doing this. The points that require 

 further observation are the following : — When does the larva naturally 

 leave the mine, in winter or in the spring ? Where does it pupate ? 

 Of what form is the pupa? Are there two broods during the year or 

 one only ? Anyone having easy access to a common, where broom is 

 plentiful, might obtain a solution of these questions. It will be seen 

 by a reference to J. W. Tutt's Britifih Lepidoptera, vol. i., p. 355-6, that 

 it has long been known that the larva of this species was attached to 

 the broom. 



On the afternoon of September 4th, 1907, I was fortunate enough 

 to find a number of the imagines oi Trifurcula ii)nuund,ella, ZelL, flying 

 over broom bushes on a Surrey common. These small moths fly 

 freely between 6 and 7 p.m. around the bushes. The flight is usually 

 not a long one, but fairly rapid, and often pendulum-like, from one 

 part of a bush to another part. Once or twice I have seen the moths 

 fly up high till they were lost to sight. At the end of each short flight 

 they alight on a broom twig and run up and down, turning with 

 marvellous rapidity, till they find a leaf, on the upper surface of which 

 they rest. If no leaf be present, which is often the case, they come to 

 rest on the twig. When resting between the flights they hold the 

 antennae outspread at right angles to the body, but when really resting 

 (sleeping?) the antennae are concealed beneath the body, which position 

 brings the white eye-caps right down over the black eyes, which are 

 then quite hidden. The wings are held rather closely to the body. In 

 the resting position the moth reminds one more of a Lithocolletis than 

 a Nepticula. I took one pair in copula, they rested back to back, one 

 partly covered by the wings of the other. 



The next day found me on the same spot, and I watched two 

 females ovipositing. The moth flies on to a broom twig and runs 

 rapidly up and down till she finds a suitable situation, when she 

 remains still whilst pressing the abdomen on to the twig and laying 

 the egg. The ovum is laid singly on the bark of the last formed shoots, 

 generally near the top, in one of the furrows of the twig. On Septem- 

 ber 11th I visited the place again and found many ova on the broom 

 twigs. Four more females were seen ovipositing. In every case they 

 proceeded as already described and always came to a standstill with the 

 head uppermost. In all cases the moth, after laying, crawled up to the 

 top of the twig and rested some time. There were several moths rest- 

 ing on the leaves and crosswise on the twigs, but these were inactive, 

 and possibly males. Nearly all the moths observed this day were rather 

 June 15th, 1917. 



