August, '10] DAVIDSON : CALIFORNIAN APHIDIDAE 375 



Lachnus almfolice Fitch. On the under side of the leaves of Alnus 

 rhombifolia. 



Cladobiiis saliciti Harris. The eggs of this species are deposited in 

 large quantities on the twigs of willow or poplar in November 

 These hatch before the end of January, the newly-hatched larvae 

 assembling in masses at certain places to feed on the twigs. The 

 leaves of the tree do not develop for two weeks after the insect 

 hatches. In the fall this insect increases with great rapidity not- 

 withstanding the heavy toll exacted by an Aphidius. 



Cladohius rufidus Davidson. On Popidus and Salix. 



CJiaitophorus viminalis Monell. I have taken this species in both 

 sexes in the fall and as late as late November. It feeds on various 

 species of willow. 



CJiaitopliorus pop^difoUce Fitch. The colonies of this species have 

 the largest numbers of individuals just before the leaves of their 

 food-plant begin to fall. At this time there are two types of apterous 

 viviparous females, both green, but one paler than the other. The 

 paler variety gives birth to the small red males, while the darker form 

 begets females winged and wingless. The males are winged and are 

 of a claret color, quite a little smaller than the alate females, which 

 latter are green. Males begin to emerge fully winged from the 

 25th of October on. At this time males and females were about ecpial 

 in numbers and remain so until the leaves drop, when all disappear. 



The alate male. Length, 1.85 mm. Breadth, .85 mm. Wing ex- 

 pansion, 5. mm. Antennal joints — III, .45 mm. ; IV, .28 mm. ; V, 

 .22 mm. ; VI, .08 mm. ; VII, .4 mm. Antenna yellow, last three joints 

 red. Sensoria on all joints except I, II and VII. Eyes bright red. 

 Head, prothorax, thoracic lobes dusky red. Pale part of the pro- 

 thorax flesh-colored. Legs yellow, hind femora reddish. Abdomen 

 brick-red, with a darker transverse dorsal bar on each segment at- 

 taining the margin on the two caudal segments. Cornicles yellowish- 

 red, expanded at the base, slightly longer than broad at their bases. 

 Tail small, globular, gray. Caudal appendage pale, drawn out. 

 Wings large, third discoidal obsolete at base. Insertions of wing 

 3'ellowish. Stigma gray. Veins reddish-brown. 



Comparative Mfasuremexts of the Alate Male and Female 



Length body, 

 Breadth body. 

 Antennae, 

 Cornicles, 

 Expanse wings, 



CJiaitopliorus nigrce Oestl. (?). I took a small black Chaitophorus 



