PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 



389 



foodplants are known. The larvae have been collected at Pabna in the 

 latter part of August, at Dacca in July and September and at Jorhat, 

 Assam, in August, in all cases in sugarcane. All of them developed into 

 moths in August, September and before 2nd October. Mr. S. E. Gupta 

 sent 138 larva? and 12 pupse from Jorhat in August 1918. Ninety- 

 two of them developed into moths, 59 females and 33 males, between 

 23rd August and 26th September. Almost all of them were tried for 

 eggs in the Pusa Insectary without success. 



The full-grown larva is about 30 mm. long and cylindrical in shape. 

 The head is red-brown, shiny. The prothoracic shield is large, dirty 

 brown in colour and divided longitudinally by a faint marking. The 

 general colour of the body is pale yellowish-white. The marking and 

 warts on the body show the following variations : (1) There may be 

 two broad slightly pinkish-brown stripes on each side of the body, one 

 subdorsal and the other supraspiracular, the dark brown large shiny 

 warts being situated on these stripes ; such larvae closely resemble the 

 active larvae of Diatrcra venosata. (2) The stripes may be indistinct, 

 the warts only being very prominent on the skin. (PI. 52, f. 1). These 

 larvae too are liable to be mistaken for those of Diatrwa venosata. (3) 

 The warts may be altogether indistinct, the stripes only being present 

 in an interrupted manner and the two stripes on each side approaching 

 each other at intervals (PI. 53, f. 1). Such larvae are hable to be confused 

 with those of Chilo simplex. (4) Both stripes and warts may be indis- 

 tinct. Of these four types of larvae the second is the commonest. The 

 morphological characters given in the key of the larval forms, on which 

 the differentiation is based, are always constant. 



The caterpillars occur in large numbers in individual jilants which 

 are literally riddled, some dust being thrown out from side-openings 

 in the stem. They pupate inside the affected stems near previously- 

 made holes through which the mature pupa wriggles out before the 

 moth emerges. The pupa is bro^vn and the characters given in the key 

 of the pupal forms distinguish it sufficiently. Of all the internal borers 

 so far observed this is the most injurious to grown-up canes. 



Diatma sp. (C. S. 1674). 



Plates 55, 56. 

 Foodplants — 



Sugarcane — Dacca ; Pusa. 



Rice — Pusa ; Karimganj, Sylhet. 



This species is active from about February-March to October -Novem- 

 ber, the winter being passed in hibernation in the larval state. (Plate 

 53, fig. 2). 



