THE MONTHLY BULLETIN. 65 



nevertheless, after death, are found to contain embryos. Regarding 

 the fall migrants and males it may be said that, provided the foliage 

 of the winter hosts is nol prematurely blown off by storms, it does not 

 require a large number of these to insure an appreciable egg infestation. 



Prom four to ten generations appear to occur on the rush, the aphids 

 settling on both sides of the blades, locating in colonies, chiefly not far 

 from the tips. 



The reddish-brown plum aphis, Ehopalosiphum nympheas Linn., which 

 occurs on plums of both European and Asiatic origin, uses the cat-tail 

 abing with many other water plants, Alisma, Nymphea, Potamogeton, 

 etc., as summer hosts. The spring and fall migrations occur at about 

 the same time as for the mealy aphis. The spring migrants are more 

 prolific than those of the latter species and therefore the rush colonies 

 grow faster. They are, however, more readily disposed of by predators 

 and in the majority of cases are soon wiped out, while the smaller 

 colonies of the mealy aphis more frequently escape. 



The grain aphis, Macrosiphum granarivm Kirby, colonizes Typha 

 during the summer and fall, winged forms arriving in May and June 

 and another such generation departing in the late autumn. This species 

 is very proline, but its numbers are heavily depleted through predators. 

 In spring it is common on grasses and it appears in California to 

 pass the winter in the viviparous form on these hosts. Gillette and 

 Bragg, in Journal of Economie Entomology, February, 1915, page 103, 

 state that in Colorado granarium deposits winter eggs on rose bushes. 

 This procedure may also occur in California along with the viviparous 

 winter-feeding form. 



Aphis ur. nee Fabricius, the oat aphis, is another grass species that may 

 be found, often in large colonies, on cat-tail during summer and fall. 

 In winter and spring it is found in California on grains and grasses. 

 It also virulently attacks corn, and both on corn and cat-tail is most 

 commonly found concealed under the outer leaves near the base of the 

 stalk. Normally, Aphis a/vena winters in the egg stage on rosaceous 

 plants, including the apple, but in California viviparous forms occur 

 during the winter on grasses and in early spring these attack grains. 

 During the summer and fall, after the grasses have dried up and the 

 grains have been harvested, corn and cat-tail are the principal hosts. 

 Few winged forms are produced among the cat-tail colonies and with 

 the advent of the winter rains large numbers. of the wingless individuals 

 are submerged. 



A small, black aphis, probably Aphis gossypii Glover, also occurs in 

 small numbers during the summer and fall months, migrating forms 

 appearing at the end of October. 



Red spider-mites, Tetranychus sp., feed, sometimes in abundance, on 

 Typha during the summer months. 



In the light of the foregoing it is obvious that the cat-tail rush harbors 

 pe^ts of notable importance, and that it should be looked upon with 

 disfavor by persons engaged in growing crops which may be attacked 

 by insect pests. 



