PLANT-HOUSE ALEYRODES. I37 



larva. There are four pairs of stigrnata, three on the thoracic 

 region and one on the eighth abdotn'rnal segment. The stigmata 

 of each side are connected by a ventral trunk, but the dorsal 

 girdles are not complete. The dorsal longitudinal trunk is not 

 complete in the imago, but long branches extend anteriorly from 

 the anal spiracles, and posteriorly from the thoracic spiracles, on 

 the dorsal side of the body. 



REMEDIES. 



The experience at this Station in destroying the plant-house 

 Aleyrodes is similar to that at the Connecticut Station and the 

 following from their report* will serve to express the situation 

 here. 



"Spraying. — In 1895 the writer (Mr. W. E. Britton) used 

 whale-oil soap solution (i pound of soap to 5 gallons of water) 

 in the form of a spray on the under surface of the leaves to kill 

 the nymphs. The result was successful, but on account of the 

 disagreeable odor of whale-oil soap, it was discarded. Fir-tree 

 oil (one-half pint in 2 gallons of water) gave excellent results 

 when the plants were thoroughly sprayed with the solution. The 

 adults and nymphs which were moistened by the spray were 

 killed. The cost of the m^aterial, however, makes the treatment 

 an expensive one and precludes its use on a large scale. Fir- 

 tree oil has a pleasant odor and is not objectionable to use in a 

 green-house of ornamental plants or even in a dwelling. 



"A fine spray of kerosene and water (15 per cent, kerosene) 

 was then applied to the tomato plants on sunny days, by means 

 of a 'kerowater' pump, with good results in killing the insects. 

 But kerosene, like whale-oil soap, has an unpleasant odor, and 

 occasionally causes a slight injury to the foliage. Even when 

 not at first apparent, the leaves in some instances took on later a 

 brown or reddish color not indicative of health, and some ot 

 these finally dropped. 



"Early in 1901, we began spraying the tomato plants with 

 common soap and water, dissolving one pound of soap in eight 

 gallons of water. This seemed to be best, all things considered, 

 of any of the sprays. Not only was it effectual in killing all 

 adults and nymphs with which it came in contact, but it was 



♦Report of the Connecticut Agricultural Experiment Station for 1902. 



