20 



BULLETIN 100, U. S. DEPABTMENT OF AGEICULTUEE. 



to the size of the body. When on the lower surface of the leaflet it has 

 the habit of resting with the head directed straight toward the 

 peduncle of the leaflet. In July and August, in which months this 

 insect is most abundant, as many as 400 individuals may be found on 

 one leaflet, 5 per cent of which will be resting on the upper side. At 

 this time it is much sought after by ants, which feed on the liquid 

 excreted by it. A large red and black species, determined by Mr. 

 Theodore Pergande as Formica obscuriventris Mayr, is a very common 

 attendant. Formica subsericea Say also attends it. The sweet excre- 

 tions of the aphis attract many flies of the families Muscidaa, Anthom- 

 yiidae, Oscinidse, and Syrphidas, many large bees including the 

 honeybee, wasps of the family Ponrpilidse, and parasitic wasps of the 

 families Ichneumonidse and Braconidse, and numerous smaller forms 

 of insect life. The author first observed this aphis on July 20, 1911, 

 at San Jose, Cal. 



life history and technical descriptions. 



The Viviparous or Asexual Forms. 



The stem-mothers hatch as soon as the buds start to swell, about 

 the 1st of April. These develop into winged aphides and pass their 

 life cycle in from 25 to 30 days, according to temperature and the 

 amount of food supply. The viviparous aphis passes through four 

 molts, becoming winged after the final one. Table VII indicates the 

 life cycle of 38 individuals of the summer generations. 



Table VII. — Life-cycle of viviparous females of Monellia caryae, summer generations, 



San Jose, Cal., 1912. 



No. of indi- 

 vidual. 



Gener- 

 ation. 



Date of 

 deposi- 

 tion. 



Date of 



acquiring 



wings. 



Life 

 cycle. 



No. of indi- 

 vidual. 



Gener- 

 ation. 



Date of 

 deposi- 

 tion. 



Date of 

 reaching 

 maturity. 



Life 

 cycle. 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



15 



16 



17 



18 



19 



II 

 II 

 II 

 II 

 II 

 II 

 It 

 III 

 III 

 III 

 III 

 III 

 III 

 III 

 III 

 III 

 III 

 V 

 V 



Apr. 22 

 22 

 22 



May 1 



1 

 1 



13 

 13 

 13 

 13 

 13 

 13 

 13 

 13 

 13 

 13 

 June 22 

 22 



May 12 

 12 

 12 

 20 

 22 

 23 

 23 

 29 

 29 

 29 

 29 

 29 

 30 

 30 

 30 

 30 

 30 



July 4 

 7 



Days. 

 20 

 20 

 20 

 19 

 21 

 22 

 22 

 16 

 16 

 16 

 16 

 16 

 17 

 17 

 17 

 17 

 17 

 12 

 15 



20 



21 



22 



23 



24 



25 



26 



27 



28 



29 



30 



31 



32 



33 



V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 V 

 VI 



June 22 

 23 

 23 

 24 

 24 

 24 

 24 

 24 

 24 

 25 

 25 

 25 

 25 

 25 

 27 

 27 

 27 

 27 



July 13 



July 7 



7 



7 



7 



7 



7 



8 



8 



8 



8 



8 



8 



8 



9 



10 



10 



10 



10 



Aug. 1 



Days. 

 15 

 14 

 14 

 13 

 13 

 13 

 14 

 14 

 14 

 13 

 13 

 13 

 13 

 14 

 13 

 13 

 13 

 13 

 19 



34 



35 



36 



37 



38 



Thus, the second generation requires 20 days, the third 16 or 17, 

 and the fifth 15, in which to complete the life cycle. Records of the 

 fourth generation were not obtained owing to premature death of all 



