66 Psyche [April 



BIOLOGICAL NOTES ON PARTHENOGENETIC MACRO- 

 SI PHUM TANACETI LINNAEUS 



(APHIDID.E, HOMOPTERA)! 



By Leopoldo B. Uichanco 



College of Agriculture, university of the Phillipines 

 Los Banos, p. I. 



The data on which the present paper is based have been 

 collected while I was conducting experiments on Macrosiphum 

 tanaceti, in connection with another problem. The work was 

 done at the Bussey Institution during the earlier part of the 

 summer of 192 L A few of the facts brought out in the discussion 

 are somewhat fragmentary, and require more thorough investi- 

 gation; but, in view of the scarcity of such records of aphid 

 behavior in the literature, they have been introduced here, in 

 the hope that they may help to stimulate further research along 

 these lines. 



I. Ecdysis. There are no appreciable differences in the 

 behavior of Macrosiphum tanaceti during the four successive 

 molts. No attempt, therefore, will be made in the present paper 

 to describe the methods separatel}^ for each ecdysis. Preliminary 

 to the process, the nymph ceases to feed for a few minutes, and 

 in the meantime holds with its claws on the surface of the sup- 

 porting part of the plant. The position of the insect during 

 molting has always been found to be such that the head points 

 toward the ground. The legs are spread far apart, so that the 

 prothoracic pair is directed anterolaterally with reference to the 

 insect's body; the mesothoracic, ectolaterally; and the ineta- 

 thoracic, posterolaterally. The haustellum is held close to the 

 sternum. The subcaudal portion of the abdomen almost touches 

 the surface of the plant. The antennae are directed posteriorly, 

 and are subparallel to the lateral margin, but diverge at an angle 

 of about thirty degrees above the dorsal surface of the body. A 

 longitudinal mesal rupture then appears at the head, adjoining 



iContribution from the Entomological Laboratory of the Bussey Institution, Harvard 

 University. No. 199. 



