64 



THE MONTHLY BULLETIN. 



THE CAT-TAIL RUSH, TYPHA LATIFOLIA, AS A SUMMER 

 HOST OF INJURIOUS INSECTS* 



By W. M. Davidson, U. S. Bureau of Entomology, Sacramento, California. 



The eat-tail rush is abundant in California along watercourses, in 

 ponds and marshes, and even in irrigation ditches. Very frequently 

 this water plant thrives in close proximity to orchards, and throughout 

 the long dry summers it remains green while the grasses and weeds in 

 great part begin to die off in the late spring. 



Fig 14. The mealy bug plant louse, Hyaloptt rus arundinls Fabricius, on the under- 

 side of a prune leaf. Enlarged twice. 'After Essig, Monthly Bulletin, Cal. 

 Hort. Com.) 



Perhaps the chief insect pest that feeds on the rush is the mealy 

 plum aphis, Hyalopterus arundinis Fabricius. Spring migrants of 

 this species commence arriving from the winter hosts, plums and 

 apricots, at the end of April and continue to arrive until the end of 

 July. They deposit young on the cat-tail and there ensues a series 

 of wingless generations until the middle of October, at which period 

 the winged fall migrants and the winged males are first produced. 

 The colouies, however, straggle on as late as December, the fall migra- 

 tion extending over a period of one and a half months. The winged 

 forms migrate to the fruit trees, the fall migrants depositing the egg- 

 laying females, which when mature copulate with the migrating males 

 and forthwith deposit winter eggs on the twigs. Considering the very 

 large numbers of spring migrants which find their way to the rushes, 

 the ensuing infestations on this host are remarkably small, and observa- 

 tions have shown that many migrants fail to deposit any young, but 



•Published by permission of Chief of the Bureau of Entomology. 



