MORPHOMETRIC STUDIES OF PERICALLIA RICINI F. (ARCTIIDAE) AND EUPROCTIS FRATERNA (MOORE) (LYMANTRIIDAE) INFESTING CASTOR (RICINUS COMMUNIS L.)

Progression factor for increase in head capsule width worked out by least square method for Euproctis fraterna (Moore) and Pericallia ricini F. reared on leaves of castor was around 1.5 for both species with variability of 10.21% and 17.72% respectively between successive instars indicated that growth was not exactly linear as envisaged by Dyar (1890). With respect to growth of body length of the said two species of lepidopteran insect the mean progression factor was near about 1.76. But the variability of increase in body length between two successive instars was as high as 27.93% for Efraterna and 46.42% for P. ricini and being significantly high has disproved the hypothesis of linear relation postulated by Przibram & Megusor (1928) at least for these two species of lepidopteran larvae.