256 EXPERIMENT STATION EECOED. [Vol.37 



Report on tobacco and vegetable insects, R. T. Cotton {Rpt. Bd. Comrg. 

 Agr. P. R., 5 (1915-16), pp. 86-99, figs. 5).— Particular attention was given to 

 flea-beetles, of which four species, namely, Epitrix cucumeris, Systenn basalis, 

 E. parvula, and E. fuscata, attack tobacco, ranking in importance in the order 

 named. The eggs of these beetles are deposited about the roots of the plants, 

 upon which the larvse feed, and the leaves are attacked by the adults. 



E. cucumeris, unlike the other species of the genus, is present throughout 

 the year and does a great deal of damage. Its eggs hatch in 5 days, the larvse 

 feed from 20 to 35 days, and 6 days are pa.ssed as a pupa. E. parvula, which 

 is the third in importance, usually causes injury during dry spells. Its eggs 

 hatch in 5 days and the larvje feed for from 15 to 25 days, the pupal stage 

 lasting for a period of 6 day.s. E. fuscata, which is occasionally found doing 

 damage to tobacco, is very similar in its habits to E. cucumeris. 



S. basalis, the largest of the flea-beetles that attack tobacco, is present in 

 great numbers throughout the year. Its eggs hatch in 12 days, from 20 to 35 

 days are passed in the larval stage, and 9 days in the pupal stage. Preventive 

 measures include the destruction of weeds and bushes that grow near tobacco 

 fields. The seed beds and the young plants in the field should be kept dusted 

 with a mixture consisting of 3 per cent Paris green and 97 per cent corn flour 

 or leached wood ashes. Diplumbic arsenate of lead when used as a spray at the 

 rate of 3 to 4 lbs. per 100 gal. of water also gives good result^?. When used as a 

 dust it should be applied with at least an equal amount of dry wood ashes. 



In reporting upon vegetable in.sects the author estimates that there is a 20 

 per cent annual loss due to their ravages. Two of the more abundant and 

 destructive pests were studied, namely the chrysomelld beetles Cerotoma 

 ruflcornis and Diabroticn graminca. C. ruflcomis feeds upon beans and co\\-peas 

 and when abundant strips the leaves to their veins and midribs. The damage 

 is not confined to the beetles alone, for the larvte which live in the soil around 

 the roots of the beans, feed on the roots and nodules and make furrows in 

 the subterranean portion of the stem. The eggs, which are laid in the soil 

 upon the roots of the host plant, hatch in 8 days, the larvse feed for a period 

 of from 25 to 30 days before pupating, and from 5 to 8 days are passed in the 

 pupal stage. The metliods of control consist in the collection of the beetles as 

 they first appear and spraying with a mixture of Bordeaux and arsenate of 

 lead at the rate of 3 lbs. of the latter to 50 gal. of spray. 



D. graminea is a source of injury to all kinds of truck crops, breeding as it 

 does continuously throughout the year. The principal damage is done by the 

 adult beetles, which feed on the foliage and flowers of the tender young plants; 

 the larvfe feed on the roots of a number of plants, which they may seriously 

 weaken. The eggs are deposited in the soil about the base of the plant and 

 hatch in 8 days. The larvse, which feed for a period averaging 22 days, gener- 

 ally attack the roots from the outside, but occasionally bore into the tissues 

 of the plant at the crown. From 6 to 9 days are passed In the pupal state. 

 The entire life cycle from egg to adult requires at least 3G days. 



The sweet potato root borer (Cylaa formicarius) has become a bad pest in 

 Porto Rico only in the district near Fajardo known as " Las Cnbezas," although 

 present in small numbers in many parts of the island. The sweet potato 

 scarabee {Cryptorhynchus batatw) has also done comslderable damage to sweet 

 potatoes in Porto Rico. 



" Experiments with plant lice and lace bugs on peppers, eggplant, and cucum- 

 bers .showed that blackleaf 40 applied at the rate of 1 fluid ounce to 8 gal. of 

 water plus 0.5 lb. of whale-oil soap gave perfect control. Arsenate of lead 

 applied at the rate of 2.5 lbs. to 50*gal. of water gave excellent results in the 

 control of the leaf-feeding larvse of the moth Xylomeges sunla and the leaf- 



