58 
Psyche 
[March-June 
SOCIAL BEHAVIOR IN HOMOPTERA 
By August P. Beilmann 
Missouri Botanical Garden, St. Louis, Missouri 
The literature relating to parental solicitude in the sub- 
social insects began, according to Bequsert, with the writings 
of Herbst and Modeer in 1764. Most observations, however, 
have been reported during the last forty years. Bequsert 
(1) lists but one case of parental care in the Homoptera. 
The following observation is of interest, since it concerns 
the terrapin scale ( Eulecanium nigrofasciatum) ; hardly a 
promising subject for the development of social habits. 
During the spring of 1932 heavy infestations of this scale 
were found on hawthorn and sycamore. Since dormant 
spraying had proven ineffective, these insects were being 
watched to learn the emergence date of the young. For this 
purpose one small undernourished hawthorn was selected, 
since its convenient location permitted frequent observa- 
tions. On three successive mornings in June the young were 
seen to emerge in a body at 10 o’clock and move upward 
toward the new growth. When an examination toward 
evening failed to disclose their destination, it was assumed 
that these individuals were experiencing an unusual mor- 
tality rate. However, more young made their appearance 
the following morning, and continued to move about during 
the sunny hours. About 4 o’clock very few could be found, 
although some had settled on the foliage. It was then ob- 
served that a few stragglers were returning to the adult 
scales and after slight hesitation were crawling underneath. 
Again on the third morning, the nymphs appeared at one 
time and began their journey up the branch toward the new 
growth. Observations were more frequent during the after- 
noon and an additional number were found permanently 
located on the leaves. However, about 3 :30 P. M. the general 
movement of the larvae was reversed. They began to come 
down the branch — for some of them a journey of three feet — 
and to disappear beneath the adult females. Within twenty 
