December, '19] 



BAKER: GOOSEBERRY APHIS 



435 



Alate viviparous Form 



It is interesting to note that this form occurred in every generation 

 in which specimens were reared from the second onward. Part of the 

 offspring of the stem mothers thus became winged. All specimens of 

 this form which were placed upon gooseberry in the experiments died 

 without reproducing and this would seem to indicate that an alternate 

 host is necessary, at least to certain individuals. 



Description 



Fifth Instar (adult). — Color dark green, head and thorax brownish; ej-es dark 

 brown. .Antenna", distal part of femora and tibiae and the tarsi brownish. Wing 

 veins margined with brown. Cornicles pale. 



Length from vertex to tip of cauda 1.44 mm. Forewing 3.2 mm. long, 0.88 mm. 

 broad at the stigma. Length of the antennal segments and cornicles is given in the 

 following table. There is considerable variation in the size of the specimens and the 

 number of sensoria and this is indicated by the variations in the table. Vertex and 

 antennal segments armed with a number of capitate hairs; similar ones also present 

 on the legs and abdomen, and a few upon the thorax. Cornicles flanged and dis- 

 tinctly imbricated, shghtly swollen in their distal portion. Cauda constricted near 

 base, minutelyse tose and armed usually with five prominent hairs. Slight antennal 

 tubercles are present on the head. 



Table op Measdbbments of the Antenna of the Alate Form 



Intermediate 



One intermediate was available for study. This was taken in the 

 field by Mr. Simanton. We are unable to give, therefore, anything 

 in regard to its occurrence or reproductive activities. 



Description 



Color similar to that of the apterous' form. Longth from vertex to tip of rauda 

 1.29G mm. Width, 0.688 mm. Form flat with the thorax l)road giving a shoulder 

 effect not found in the aptcrou.s form but apparently without distinct wing rudiments. 

 Antenna' as follows: Segment III, 0.384 mm. and armed with lr> sensoria; 1\', 0.208 

 mm. and without sensoria; V, 0.208 mm. and with only the distal scnsorium; V'l 

 (O.OS mm. +0.432 mm.). Cornirlc, 0.224 mm. Cauda, 0.192 mm. Beak extending 

 beyond the second pair of coxsc. Body armed with the usual hairs. 



