408 Records of the S.A. Museum 



before leaving the stem. The bugs are shy during copulation and ovi])osition, 

 and are rather easily disturbed in either act. 



Period of Oviposition. In a jar containing one male and three females, 

 the latter were simultaneously depositing eggs on November 1st ; each laid only 

 a few eggs a day, oviposition being most active after mid-day, when the sun was 

 shining into the laboratojy ; at this time of day the male seemed greatly excited, 

 frequently stridulating, poising beneath the females, and attempting to clasp 

 them from below. On November 20th one of them, which had completed oviposi- 

 tion, was floating venter uppermost at the surface, apparently unable to maintain 

 its poise, and shortly died ; on this date the male was again in copula with 

 one of the remaining females, both of which continued laying until about Novem- 

 ber 22nd, on which date the first of these nymphs hatched. The second female died 

 on the 24th, and all weed was now removed from the vessel, so that the surviving 

 female, which had not completed egg-laying, had perforce to cease ovipositing. 

 The male perished on the 29th, but the female remained quite healthy for the 

 following three weeks; at the expiration of this tim'e a fragment of Potamogeton 

 was dropped into the jar, and the interrupted oviposition was immediately con- 

 tinued, two eggs being laid in rapid succession. The survivor lived until the 

 middle of January, 1923. 



The Nidus. A plant stem or leaf of sufficient thickness to accommodate 

 the eggs, and which the ovipositor is capable of drilling, is utilized if such be 

 present; when indigenous Potomogeton and Myriapli\jUum are growing in 

 localities favoured by Anisops the stems of these plants are usually found to 

 contain eggs. 



As an experiment a gravid female was isolated in a jar containing only 

 small plants of Vallisneria spiralis, the thin leaves of which are ill suited for the 

 reception of the ova. A great number of slits in the leaves indicated abortive 

 attempts to prepare suitable receptacles, and the eggs deposited in this nidus 

 were but partially concealed, so that it was possible to photograph them in situ 

 (pi. X, fig. 3-4). 



Period of Development. About a fortnight after deposition the eggs 

 exhibited the first traces of the red eye pigment of the enclosed embryo, and in 

 another week the nymphs emerged. This period for incubation obtained with the 

 water at a mean temperature of 67° F., but the time varies according to the 

 temperature of the water and the season of the year ; eggs deposited in December 

 developed more rapidly, the eye-pigment appearing in a few days. The skin is 

 moulted five times during the metamorphosis, the first four iustars each occupy- 

 ing about a week, the fifth a little longer. In aquaria the individual variation 

 in the periods between moults was as follows: — First, 7 days; second, 7-8 days; 



