RY VERA IRWIX SMITH. 511 



cycle of any of the titratiomi/iidae. Jlost of them content themselves with rather 

 vague statements, as. for instance, -that "the larvae hibernate, and development 

 takes place in the spring- and summer."' Tragardh, in his description of Paclii/- 

 (jatiter miiiuti.'-sima (1914) makes the observation that during the summer only 

 small larvae can be found, from which fact the deduction is drawn that only one 

 generation is produced annually, which hibernates in the larva-stage, conforming 

 to the aeeount given by Perris (1870) concerning Pachygaster pini. Cros, in his 

 interesting observations on the larval habits of Stratiornyia anubis (1911), records 

 that, of a dozen larvae collected on the 22nd October, 1903, four yielded ima- 

 gines in the following June, while from twenty-six larvae collected on the 31st 

 December, 1909, hve flies were obtained successively on the 25th .June, and on 

 the 4th July, 1910. But he gives no account of the fate of the remainder of 

 the larvae. 



Xonc of the larvae of Metoponia riibriceps have grown very much during 

 their period in captivity, and some time must elapse before it is 23ossible to de- 

 termine the normal time occupied in larval development. However, it is already 

 clear that, although two broods of flies appear annually, the larval period re- 

 quires more than six months for its completion, and very probable that it re- 

 quires considerably longer than twelve months. This may be deduced from the 

 very slow gi-owth of larvae in captivity, and the fact that larvae, already more 

 than half-grown when taken in November, show no sign of pupating in the fol- 

 lowing Sejitember. Although it is not safe to arrive at definite conclusions from 

 larvae kept under abnormal conditions, these conclusions are borne out by obser- 

 vations in the field, since small larvae are found at all times of the year, and 

 larvae less than 5 mm. long five months after the last appearance of the adult 

 flies. The smallest larva found, being only a little more than twice the size ot 

 the egg, was probably still in the first larval instar when taken, one month after 

 the appearance of the imagines. It seems reasonable to assume that larvae of 

 this, and ]ierhaps the 3 and 4 mm. lengtli. hatched from the egg during the sea- 

 son in which they were taken. 



Unfortunately, no eggs were found in natural conditions, and, though several 

 batches were obtained from females captured in glass tubes during the past 

 autumn, none of them hatched out. 



^'arious methods of keeping them were adopted — on damp blotting paper 

 over a layer of damp soil, in a covered glass pot; on growing rhizomes of paspa- 

 lum grass ; directly on damp soil ; or kept in the tube in which they were de- 

 posited. In most cases they were covered up from the light, and care was taken 

 to prevent them from becoming completely dry. Under drj- conditions they soon 

 shrivelled up, while, when conditions were at all damp, the eggs were continuous- 

 ly thickly coated with fine beads of moisture, and many of them were found to 

 be infested with fungus after a short time. However, a fair number retained 

 their normal sliape and appearance for ten weeks or more, but in no case did 

 they show any sign of development. It is possible that all these eggs were in- 

 fertile . 



Ovipositinn. 



Gravid-looking females taken during the morning, between 10 and 11 o'clock. 

 usually oviposited vei-y rapidly, the egg-laying being finished before midday. 

 Usually the eggs were laid on the side of the glass tube, sometimes on cotton- 

 wool. In one instance they were placed in a single, fairly even row, along the 



