98 
Transactions of the Boyal Society of South Africa. 
forms have the anal ring with 6 hairs and the caudal lobes + similar. The larvae 
of the whole series are of the same type and all have 6- jointed antennae. 
Several lines of development are apparent in the series, but the most striking 
characteristic is illustrated by the acquisition of additional antennal segments in the 
adult ? . For instance, in Ripersia s. str. the adult ? retains the original larval 
number, i.e. 6, but in Phenacoccus the adult ? has 9, the additional segments 
appearing with the ecdyses. 
I have attempted to indicate the relationship between the genera by isolating' 
them to form the tribe Pseiulococcini. 
lUper.<tia, Pseudococcuft, and PJienacoccus are established on antennal characters ; 
the remainder, which are the more modern genera, upon others. Strictly speaking 
the three first mentioned should retain their Signoret significance in which Bipersia 
Sign, has 6-jointed antennae; Pseudococcus Westw. (which replaces the Dactylopius 
Costa" of Signoret) 8-jointed antennae ; and Phenacoccus Ckll. (= " Pseudococcus Westw." 
of Signoret) 9-segmented antennae. This arrangement accommodated the insects 
known to Dr. Signoret very well, and the fact that there was no genus made for 
strictly 7-jointed forms was obviously due to the lack of the insects showing that 
character. Had this antennal form proved a satisfactory generic character the 
establishment of a genus to include those insects with 7-jointed antennae in the 
adult ? would have completed the series ; and the separation of species into the four 
genera would have been extremely simple. In reality this could never be done with 
the Pseudococcini, for a number of different conditions influence the antennal 
character of the adult ? , which must therefore be considered as an unstable 
character, and, as such, quite unsuitable to retain generic significance. 
The majority of the species described in the genus Ripersia are reported from the 
nests of ants, and the genus has been extended to include insects with 7-jointed 
antennae as well as those with 6. Strangely enough other forms, with 7-jointed 
antennae, which are found on plants, are included in Pseudococcus. But the fact that 
insects are found below stones or in the nests of ants cannot have this influence, 
or else, on occasion, P. citri and P. adonidum must also be Ripersia spp., as they 
have been found in ants' nests in Massachusetts (King and Tinsley, Psyche, p. 297, 
1898), If the genus Ripersia can be extended to include insects possessing 7-jointed 
antennae (because there is no special genus for the 7-jointed forms) can we still 
extend its bounds to include a form such as Ps. transvaalensis described later in 
this paper, which has adult females with 6-, 7-, or 8-jointed antennae? 
Climatic or seasonal variations may have an effect on the antennal character of 
insects in this series. Thus, in Ps. agrifoliae Essig and Ps. trifolii Forbes we have two- 
distinct generations, a summer form in which all the adult females have 8-jointed 
antennae, and a winter generation in which all the adult females have 7-jointed antennae. 
Again, in Phenacoccus acericola King, we apparently have a similar condition, the summer 
form being 9-jointed and the winter form with 8 segments. Obviously we cannot place 
the two generations in the last-mentioned case in two different genera {Phenacoccus and 
Pseudococcus). 
1 am inclined to associate the smaller number of antennal segments in these cases 
with retarded metabolism, as this is always found in the winter forms. Perhaps we can 
account for the new form of Ps. citri, which I describe later as var. phenacocciformis in a 
similar manner. 
I repeat that the antennal condition in the Pseudococcini cannot retain generic 
significance and that other characters must be utilized. Throughout the whole tribe w& 
must include in the same genus forms with 6- to 9-jointed antennae, or perhaps 6- to 10-, 
for Ceroputo pilosellae Sulc. has the antennae 9- or 10-jointed. 
This must be applied to those genera which are founded upon other characters. For 
instance, in Tylococcus Newst., which is characterized by the presence of projecting, 
marginal protuberances, the type (T. madafiascariensis Newst.) has 8-jointed antennae. 
