410 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



maximum. We have observed it breeding abundantly on rhododen- 

 dron in the Rochester parks and in private grounds at Ithaca. 



We have also received specimens from nurseries at Lynbrook, Long 

 Island, on rhododendron, and from Franklin Park, Boston, Mass., on 

 mountain laurel. In April 1908, eggs were found in abundance on wild 

 rhododendron at Port Jervis, N. Y. 



Injury 



The leaves are disfigured on the underside along the midrib by the 

 brownish scabs which cover the eggs, as described below. The great- 

 est injury is caused by the nymphs and adults feeding on the under 

 surface of the leaf. They suck the sap, causing a lighter colored spat- 

 tered appearance on the upper surface, often with consequent drying 

 and shrivehng of the leaf. The sale of rhododendrons is also some- 

 times hindered by the unsightly appearance of the undersides of the 

 leaves, due to the excrement left there by the insects. 



Life History 



Egg. — 5.54 mm. long by .24 mm. wide. It is flask-shaped with the 

 neck bent to one side. The anterior end is obliquely truncate and 

 provided with an oval lid. This lid has a submarginal ridge which 

 encloses an oval impressed area. The egg is smooth, without sculpture, 

 and is white, except near the anterior end where it is somewhat brown- 

 ish. The eggs are usually inserted in a more or less irregular row along 

 the midrib on the underside of the leaf, but occasionally in the leaf a 

 short distance away from the midrib, on either side. The leaf tissue 

 surrounding the egg becomes hardened and corky, but this hardening 

 is entirely internal and makes no noticeable change on the surface 

 of the leaf. In removing the egg with a needle, this gall-like 

 growth is easily separated from the normal tissue. The lid is nearly 

 on a level with the leaf surface and is protected by a drop of a brownish 

 substance deposited by the parent insect, and has the appearance of a 

 small scab. When the eggs are abundant, these scabs are quite notice- 

 able along the underside of the leaf. Often these scabs drop off several 

 days before the eggs hatch, exposing the egg cap. The eggs are laid 

 in the newer leaves, and the winter is passed in this stage. 



Nymph. — At Ithaca, the eggs hatch in late May or early June, de- 

 pending on the weather. They have been observed hatching outdoors 

 on June 6, and had apparently all hatched by June 17. In 1908, first, 

 second and third stage nymphs were observed out of doors on June 2. 



Explanation of Plate 22 



1. Injured and uninjured leaves, showing eggs and disfiguring on underside of leaf. 



2. Eggs in position in leaf tissue, 



3. Location of eggs along midrib. 



