89 



inch (15 mm ) when contracted, and T 8 -g- of an inch (20 mm ) when fully 

 extended, the width being a little less than an eighth of an inch (3 mm ). 



The pupa, or chrysalis (see <#), is formed in a cocoon which the larva 

 spins about itself early in June — -in Washington State, constructed 

 principally of brownish castings woven together by means of fine 

 silken strands. The chrysalis itself is reddish brown in color, about 

 one-half inch long and with several rows of blackish spines cross- 

 ing the back, the last row being larger and extending further around 

 on the sides. The wings, antenme, and long sucking tube may be seen 

 folded underneath the body. 



TJie cocoon is constructed within the burrow of the larva, and usu- 

 alty made near the center of the crown of the plant; but just before 

 the emergence of the moth, 

 the pupa, like others of its $ 



kind, and with the assistance 

 of the sharp spines on its 

 back, wriggles its way par- 

 tially out of the cocoon, and 

 after the escape of the moth 

 the empty pupa skin is left 

 projecting from the former 

 home of the larva ; as shown 

 in the illustration at e. 



METHODS OF CONTROL. 



/Submersion. — F r o m the 

 observations of Messrs. Koe- 

 bele and Klee, it is evident 

 that the submerging of af- 

 fected fields, where this can 

 be accomplished, is sufficient, 

 when properly done, for the 

 suppression of the pest. This 

 means of control is particu- 

 lar!}' applicable in localities where irrigation is practiced, the best time 

 for submersion being, theoretically at least, as soon as possible after 

 the fruit has been gathered. 



It would be interesting to learn how common this practice is, and just 

 how practicable it may be in the regions most affected by the insect. 



Insecticides valueless. — Where submersion cannot be practiced, it 

 would appear that remedial measures will be very difficult of applica- 

 tion. In fact, we are confronted by much the same difficulties that 

 present themselves in our efforts to control the nearly related squash- 

 vine borer. The concealed mode of life of the larva renders the use 

 of insecticides practically out of the question, the only one that would 



Fig. 20. — Sesia rutilans : a, female moth ; b, male ; c, larva 

 at work in strawberry stem; d, pupa ; e, pupal cell in 

 stem, showing empty pupal case after escape of moth— 

 a, b, c, e, about one-third enlarged ; d, twice natural 

 size (original.) 



