March i8i)6.1 



PS r CHE. 



85;i 



long legs and anteniuif. The egg-lav- 

 ing females arc larger and have much 

 broader boflies. They deposit their 

 eggs irregularly upon the bark of the 

 twigs, especiallv about the luuls. The 

 eggs are elliptical-ovoid, less than one 

 millimeter long, greeriish or \ello\vish 

 brown when lirst laid, but gradnallv 

 changing to shining black. ' 



There is a pretty little aphis (A. 

 en(i)ivmi) living upon tlie under surface 

 of the leaves of the shrub called Burn- 

 ing Bush {Enonvtmis atropitrptireus) . 

 In autumn the oviparous females con- 

 gregate on the twigs and deposit their 

 eggs in the crevices about the Inids. 

 A ciu'ious little Callipterus wliich 

 [ found commonly' on tlie leaves 

 of Beech in central Ohio a few years 

 ago also repairs to the bark for ovipo- 

 sition, but is much more careful in 

 concealing the eggs. The vi\iparous 

 colonies are found late in summer and 

 earlv in autumn on the under sides of 

 the leaves, with more or less flocculent 

 matter about them. The sexed forms 

 develop chu'ing October, and the ovi- 

 parous females wander over the bark of 

 the twigs, limbs, and trunk, in search 

 of crevices in which to deposit their 

 eggs. When a suitable place is found 

 the egg is laid, and is then driven into 

 position bv the following method. The 

 insect so places herself that her hind 

 legs easily touch the egg ; then standing 

 on her foiu" front legs, she brings the 

 two hind ones down upon the egg in 

 rapid succession, striking with consid- 

 erable force. This serves the double 

 purpose of pushing the egg into place, 



and ot drawing out a viscid secretion 

 with which it is covered into a tluead- 

 like silverx' film so similar to the sur- 

 rounding bark that it is difficult to 

 detect the difl'erence. A minute anil a 

 half to two miimtes are spent in this 

 process. 



Recent observations have shown that 

 a number of species of aphides live upon 

 various trees during autumn, winter, 

 and spring, but for the summer season 

 migrate to more succulent herbaceous 

 plants. The best authenticated exam- 

 ple of this is the Hop Aphis {P/iorodo// 

 ///iiii/i/i) which was carefully studied 

 both in Europe and Ameiica by Dr. 

 C. V. Riley. The life-history of the 

 species is briefly this. The insect passes 

 the winter in the egg state on plum 

 frees. In spring each egg hatches into 

 a small aphid that sucks the sap from 

 the expanding leaves. This is the so- 

 called stem-mother. She becomes full- 

 o-rown in a week or two and then begins 

 bringing forth living young at an average 

 rate of about three each day, continuing 

 the process until she has becoine the 

 mother of a hundred or more rapidl\- 

 tleveloping aphides. Each nf tliese in 

 turn gives birth to other young in the 

 same way. Three generations of these 

 parthenogenetic forms are produced 

 upon the plum, the last becoming 

 wingetl and deserting the trees to seaich 

 for bop plants. On finding them these 

 winged migrants light upon the under 

 sides of the leaves where they stait 

 colonies; and the species contiinies 

 developing upon the hop plant through- 

 out the summer. In earlv autumn an- 



