































^' 



Larva! 



damage 



to 



cotton 



field 



may attach themselves to seed cot- 

 ton, hay, agricultural implements, 

 or even to man. Larvae may he 

 spread by the movement of soil, sod, 

 1 misery stock, and root crops, such 

 as potatoes. Hay harvested from 

 infested tields in late summer and 

 fall may contain viable eggs. 



DAMAGE 



The principal damage is caused 

 by larvae feeding on the roots and 

 underground stems of plants. 

 White-fringed beetles do not usu- 

 ally cause uniform damage over 

 large continuous areas. Crop in- 

 jury may range from just a trace in 

 one part of a field to destruction of 

 a crop in a nearby held. 



In general, plants with main 

 roots (tap roots) are damaged more 

 severely by the larval stage of the 

 insect than those with fibrous roots. 

 The larvae may sever the main root 

 while they are feeding. On root 

 crop-, such as potatoes, carrots, and 

 turnips, they burrow directly into 

 the roots, or tubers, and destroy the 

 market value of the crop. 



The larvae and adults do not al- 

 ways feed on the same plant species. 

 Many of these plants or their close 

 relatives are widely distributed in 

 the United States. Plant hosts will 



therefore not be a limiting factor 

 in the spread of these insects. 



In the held, white-fringed beetle 

 adults have been found to feed on 

 more than 170 species of plants in- 

 cluding held, garden, and truck 

 crops, weeds, oranmental shrubs. 

 flowers, wild bushes, vines, and 

 trees. Larvae have been observed 

 feeding on 240 species of plain-, 

 some of the most common being al- 

 falfa, beans, carelessweed, carrot, 

 chrysanthemum, cliuf a. clover, cock- 

 lebur, corn, cotton, cowpea, curled- 

 dock, Irish potato, lupine, mustard, 

 oats, peanuts, peas, ragweed, soy- 

 bean, strawberry, sweetpotato, to- 

 bacco, and velvetbean. The larvae 

 also feed on the roots of young 

 woody plants such as peach, pecan, 

 tung. and willow, as well as on parts 

 of dead plants in the soil. The 

 adult beetle prefers to feed on 

 plants Inning broad leaves. 



A number of factors may influ- 

 ence the intensity of an infestation. 

 The beetles are more abundant — 

 and damage is greater — in well- 

 drained, sandy loam than in heavy 

 clay soils. An unusually dry sum- 

 mer may retard the beetle's develop- 

 ment. A heavy rainfall, which 

 saturates the soil for about a week, 

 kills many young larvae. 



630S38' 



62 



