312 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



beetles below the destructive point. In Connecticut a few specimens only of this 

 beetle were found on grass and weeds, on the edge of a nursery where new residences 

 are being erected. W. E. B. 



Feeding Punctures of Insects. At the meetings in Toronto, last year, I was asked 

 the nature of the feeding puncture of the greenhouse whitefly {Trialeurodes vaporal 

 riorum West.) and was unable to give a definite statement regarding it. As 

 stated at that time, the aphids in most cases select the soft bast of the vascular 

 bundle. Allen has shown that the middle lamella consists really of two layers, one 

 contributed by the secretion of each of the daughter protoplasts. The cell plate 

 does not constitute the middle lamella but splits to form the plasma membranes of 

 the daughter cells. It is along the cleavage plane of the middle lamella that the 

 setal tract of the plant louse proceeds and along this tract the setal secretion is laid 

 down. While the feeding does not, therefore, injure the mesophyll cells this se- 

 cretion often has a distinct reaction, the cells becoming enlarged, oedematous and 

 devoid of chloroplasts. The reaction of this secretion appears to vary with different 

 species and different hosts. Hargraves has studied the punctures of the green- 

 house whitefly and it seems evident that this insect selects similar tissues for feeding. 

 Trialeurodes vapor ariorum, then, should be grouped with the commoner aphids as 

 to tissue selection and not with such forms as the red spiders which feed on the con- 

 tents of the epidermal cells or a few cells immediately underlying them. 



A. C. Baker, 

 U. S. Bureau of Entomology 



Sea Coast Flea Beetle (Disonycha maritima Mann.) Injurious to Sugar Beets in 

 Sacramento Valley, California. While conducting investigations on the beet leaf- 

 hopper (Eutettix tenella Baker) in the Sacramento Valley, Mr. G. Wright, formerly 

 Agriculturist of the Alameda Sugar Company, and the writer visited some beet 

 fields which were seriously injured by one of the Halticini, Disonycha maritima 

 Mann. The foliage was riddled with holes and from 1-2 dozen beetles were found 

 between the petioles at the crown of the beet or below lumps of soil near the beet 

 root. The beetles also gnawed holes in the beet root. The pest was generally 

 distributed over 157 acres of sugar beets near Knights Landing on May 27, 1919. 

 The beet fields were visited again on June 16 and 22, but the beetles were rarely 

 found. Trips were taken to the same fields in July and August but the beetles had 

 disappeared. During 1920, the same beet fields were visited on May 26-27, with 

 Mr. A. J. Basinger, formerly Entomologist of the Alameda Sugar Company, and the 

 beetles were commonly taken but the injury was not so serious as during the pre- 

 ceding spring. During the summer, however, the beetles again diasppeared. Al- 

 though all beet centers were visited in the Sacramento Valley during the two seasons 

 it was only in the Knights Landing beet district that this insect was found. 



According to the literature nothing is known of the native food plants of this 

 beetle. Mannerheim (Bui. der Naturforsch. Gesellsch. in Moscau, Bd. 16, p. 311, 

 records the habitat in California on plants along the sea coast. Horn (Amer. Ent 

 Soc. XIV, 1889, pp. 206-207) states that D. maritima occurs in California and Nevada 

 Fall (Cal. Acad. Sci. VIII, 1901, p. 157) mentions one example taken at Pomona 

 California in October. Van Dyke (Ent. News XXX, 1919, p. 244) found in the 

 cleft of the rocks along the crest of the San Bruno hills which form the southern 

 boundary of San Francisco County, fair assemblages of D. maritima during the winter. 



Specimens were kindly determined for me by Professor E. C. Van Dyke. 



Henry H. P. Severin, Ph.D. 

 Calif. Agr. Exp. Sta. 



