INSTITUTE, PUSA, FOR 1917-18 105 



observation was also corroborated by the fact that the wheat 

 obtained last year for storage experiments contained 

 Tribolium when stored; but, in the samples which were 

 unaffected by Calandra and Rhizopertha, no damage was 

 done by Tribolium, whereas, in samples which were affected 

 by Calandra and Rhizopertha, these two pests first produced 

 wheat dust in which Tribolium could breed and it was only 

 in these samples that Tribolium bred profusely. 



For the first time, at least in the Pusa area, Bruchus 

 chinensis and another unidentified 1 species of Bruchus were 

 observed to breed in the fields in pods of cowpea (Vigna 

 catjang), but only a few could be found after a good deal of 

 search. Whilst Bruchus chinensis is thus shown to be 

 capable of breeding in the field, it is essentially a pest of 

 stored pulse, to which it causes serious damage. 



Another unidentified 1 species of Bruchus was observed 

 breeding in Sesbania pods in the field, and was kept under 

 observation both in the Insectary and in the field. The 

 beetles did not breed in the stored seeds and the emergence 

 of the adults extended over a long period from February to 

 June. 



In last year's Report mention was made of an experi- 

 ment to find out the effect of sunning pea (Pisum arvense) 

 seeds affected by Bruchus affinis. Twenty-six pounds of 

 pea seeds were taken from a crop harvested from a field 

 known to be affected. Half of these were dried in the sun 

 for seven days, when their weight was reduced to 12 lb. 

 9^ oz. ; the other half was kept as a check. After a period 

 of a year, in the sunned sample the damage was one-third 

 of that in the untreated sample. Thus, although damage 

 was not entirely prevented, it was checked to a very large 

 extent. 



Insecticides. Incosopol, a contact insecticide manu- 

 factured by the Indian Cotton Seed Oil Company, Navsari, 

 was tested on Aphids, Scale-insects and Mealy-bugs, and 



1 A collection of the various Bruchid beetles reared from pulses was sent out 

 during the year for identification but the names had not been received at the time of 

 writing thia Report, 



H 



