Dec. i 5 , 1920 Tamarind Pod-Borer, Sitophilus linearis (Herbst) 441 



of the abdomen alone showing above the surface of the pulpy covering, 

 the rest of the body being concealed within the cavity. This cavity 

 is usually completed in from two to three days. The individual egg 

 cavities are then bored in the seed all around the interior of this larger 

 cavity, an egg being deposited as soon as a hole is finished. The eggs are 

 all placed as close together as possible, so that the interior of the large 

 cavity has the appearance of being lined with rows of egg-caps. From 

 12 to 50 eggs are laid in one group, the time taken for the completion of 

 the group varying from one to two weeks, according to the number of 

 eggs laid. By the time the last egg is laid the first eggs have hatched 

 and the grubs have become half grown. This habit of the female weevil 

 of grouping a number of eggs together in one seed exhibits an interesting 

 difference from the egg-laying habits of the grain weevils belonging to 

 this genus. One would naturally conclude that it was developed to save 

 energy, since it would be no mean undertaking to bore through the 

 pulpy covering and the tough seed coat for each individual egg. 



The operation of excavating the egg cavities is accomplished by a 

 combined up and down and rotary motion of the proboscis, effected by 

 turning the head from side to side while the thorax is oscillated back and 

 forth. As soon as an individual egg cavity is completed and the sides are 

 smoothed to the satisfaction of the weevil the proboscis is withdrawn. 

 The weevil then reverses its position and, inserting its ovipositor into the 

 cavity, deposits an egg, sealing it in with a plug of opaque, yellowish 

 material resembling faecal matter. In a few days this plug turns to a 

 dark yellowish brown. 



It is interesting to note that, so far as observations go, the female 

 weevil does not leave the egg cavity from the time it is started until the 

 last egg has been laid. She works day and night until the operation has 

 been accomplished unless disturbed by outside agencies. Whenever 

 she rests it is without leaving her position in the cavity. As soon as one 

 group has been finished the weevil immediately seeks out another loca- 

 tion and begins operations again. For sheer industry and continuous 

 application to the object of perpetuating its kind this weevil would be 

 hard to surpass. 



The eggs hatch at the end of three days. Previous to hatching the 

 larva may be distinctly seen through the thin outer shell of the egg. 

 This shell or skin is very flexible and undulates with the movements of 

 the young grub. It becomes somewhat wrinkled and finally breaks at 

 the bottom, allowing the grub to escape. The young larvse begin at 

 once to feed and bore through the seed, their burrows radiating from 

 the large cavity to all parts of the seed, and usually ending near the 

 shell of the seed, through which, however, they never break. 



As in other species of this genus, there are four larval instars, although 

 previous writers have erroneously attributed but three larval instars to 



