i:t88 INSECTS ETC., IXTC'RIOUS TO VARIOT'S CROPS 



to fear in the attack of E. pyricola, and only in extreme cases can the latter 

 prevent or slightly retard their growth. The case is quite different where 

 it is a question of 3'oung plants less than 4 years old. The almost simul- 

 taneous loss of a large number of rootlets may completely arrest growth and 

 bring about a premature fall of the leaves, frequently followed by the death 

 of the plant. 



Winged forms appear in autumn. In gardens and in all localities where 

 the environmental conditions are favourable to the growth of the winged 

 individuals, the outbreaks in spring and at the beginning of summer are al- 

 ways unimportant, in view of the small number of wingless individuals 

 which hibernate on the roots, while the major part of the colony migrates. 

 I'rom the month of Juh' onwards, however, the aphids increase rapidly, 

 attaining their maximum number in September, at which time the winged 

 forms appear. The departure of the winged swarms, which often migrate 

 even to great distances, also marks a period of rest for the plant, which now- 

 having nothing to fear but the few wingless aphids remaining on the roots 

 through winter, puts forth new rootlets and gathers strength to resist fresh 

 attacks. 



The winged forms stay on the leaves and trunk of the pear trees, and 

 afterwards generally take up their abode on the foliage and trunk of Alnus 

 sp., where they go through their life C5xle and produce the sexual generation. 



1052 - Galerucella cavicollis, a Coleopterous Pest of Cherry and Peach Trees 



in the United States (i). — Cushm.\nn R. a. arid Isely Divight, in United states Depart- 

 ment of Agriciilture, BulletinNo. 352, pp. 1-28, Fig. 1-9, PI. I-IV. Washington, D. C, 1916. 



In the spring of 1915, the cherry and peach plantations extending over 

 a vast area in the north-east of the United States sustained considerable 

 damage from a sudden and formidable outbreak of Galerucella cavicollis 

 Le Conte (cherry-leaf beetle). This already known beetle had never 

 previously caused such extensive injury. Among the regions which suffer- 

 ed most are the vStates of New York and Pennsylvania and the northern 

 part of Western Virginia. 



The adults attack the leaves of the cherry and peach and the fruits 

 of the cherry, gnawing them and producing fairly deep injuries. When 

 the attack is ver}- severe, the plants may be almost completel)' stripped of 

 leaves. The natural host of Galeviicella is said to be Primus pensylvanica (bird 

 cherry) which spreads with great rapidity along the road sides in the thickets 

 and on the lands formerly occupied by forests destroyed by fire, which form 

 a very favourable environment for the growth and multiplication of the 

 insect. The latter hibernates in the adult form, leaving its shelter in 

 the spring ; it mates and the female oviposits at the foot of the trees amid 

 the dried leaves and other vegetable detritus. The larvae hatch in a 

 fortnight, and when full grown, pupate in a hole which they have made 

 in the soil. The adults emerge in two or three weeks and spread through 

 the plantations where they attack the leaves and fruits. This continues 



(i) See li. June i-iiC, Xo. ;i^. (£1/.) 



