56 



CIRCULAR 270, U.S. DEPARTMENT OF AGRICULTURE 



DESTRUCTIVE PRUNE WORM 



The destructive prune worm (Mineola scitulella Hulst) has been 

 injurious only in southern Idaho, where it has become a rather 

 serious pest of prune trees. Its habits are somewhat like those of 

 the bud moth. The partly grown brown worms spend the winter in 

 small hibernacula woven of silk and placed in the smaller crotches or 

 in crevices in the bark. These worms emerge in the spring before the 

 flower buds are open and bore into the buds, feeding entirely on the 



inside and destroying 

 many blossoms. 

 They become full 

 grown in 2 to 4 weeks, 

 when they drop to the 

 ground and spin 

 loose cocoons. The 

 moths emerge from 

 these cocoons in June 

 and lay eggs singly on 

 the lower surface of 

 the prune leaves. 

 The worms hatching 

 from these eggs bur- 

 row into the green 

 prunes and cause 

 considerable injury 

 by feeding on the 

 fruit. This second 

 brood of worms be- 

 comes full grown late 

 in July or early in 

 August and produces 

 a second brood of 

 moths. Worms com- 

 ing from eggs laid by 

 these moths feed for 

 a time in the matur- 

 ing fruit and then 

 leave it and spin the 

 silken nests in which 

 they hibernate. There 

 are thus two com- 

 plete generations in a season. No satisfactory measures for control- 

 ling this pest have been worked out. 



SNOWY TREE CRICKET 



The snowy tree cricket (Oecanthus niveus DeG.) occurs throughout 

 the Pacific Nortrrwest, but is of economic importance only in southern 

 Idaho, where it does considerable harm to prunes by eating holes in 

 the ripening fruit. Early in the season the young feed on the foliage, 

 but this injury is of little consequence. About the first of August the 

 prunes are sufficiently ripe to attract the crickets, and after that time 

 both young and adults feed on them instead of on the foliage. Small 

 holes are made in the skin of the fruit, and the flesh is eaten out, 

 large cavities often being formed (fig. 67). 



Figure 65. —Bushy terminal growth of prune caused by bud-moth 

 injury. 



