216 F. \V. EDWARDS. 



pools amongst the reeds. A close examination of these larvae has failed to reveal any 

 differences whatever between them and 0. nxtadatus ; a result which is not a little 

 surprising, in view of the fact that when there are conspicuous differences in the male 

 genitalia, as there are in these two species, they are usually associated with marked 

 differences in the larvae. 



Ochlerotatus nemorosus, Mg. (tig. G a). 



This species is very abundant on Harrow Weald Common, Middlesex. The larvae 

 appear in the temporary pools in the hollows about Christmas, and become full-grown 

 about the middle of March, the first adults appearing towards the end of that month. 

 Normally, as in other related species, there is only one brood in the year, and attempts 

 to hatch out larvae in the early autunm by placing dry leaves from the hollows in 

 water have failed. Last year (1915), however, the weather conditions were 

 abnormal : an early spell of dry weather caused the pools to dry up completely by 

 the middle of April, about a month earlier than usual ; this was followed later on by 

 a very wet summer, and the hollows were filled up again and remained full for several 

 months, whereas in normal years they are dry from about the middle of May till about 

 the end of November. Under these circumstances a plentiful second brood of 

 O. nemorosus was produced in July, and the specimens of this brood weie, if anythinor, 

 even more vicious in their attacks than those of the first brood. 



Fig. 0. ►Scales from the oomb of the oightli abdominal 

 segment oiOcli\erotatns\awA*? : — (o) O. netiiorosus, Mg. ; 

 (6) O. dorsnlis, Mg. : (c) O. saliniis. Fie. 



^^ hile watching one day a number of these second-brood insects feeding on my 

 hand and ankle, I suddenly noticed that one of them was apparently a male. I at 

 once secured it, and kept a look out for others. In about ten minutes I had taken 

 three in the act of sucking, while a fourth had escaped. Probably more could have 

 been secured if time had allowed, but unfortunately I had no other opportunity of 

 visiting the locality until the mosquito season was over. A close examination later of 

 the three specimens taken showed that none of them were normal males, but all three 

 had one or more female characters on one or both sides of the body. It seems not 

 improbable, therefore, that other male specimens of various mosquitos which have 

 occasionally been recorded as biting were really partly hermaphrodite. As very fe^r 

 cases of hermaphrodite mosquitos have been recorded, it may be of interest to describe 

 these examples : — ■ 



Specimen A. — Left antenna as in male, normal. Right antenna with the basal joint 

 a little smaller than in a male : following 11 joints shorter, stouter and more hairy 

 than in a female, but more like this sex : last two joints rather elongate, but together 

 scarcely longer than the penultimate joint of the left antenna. Left palp about half 

 as long as the proboscis, its tip thickened, distorted, and hairy. Right palp as in 

 female, normal. Hypopharynx normal, as in female. Both mandibles absent. . 



