138 MISC. PUBLICATION 434, U. S. DEPARTMENT OF AGRICULTURE 



FLEA BEETLES 



The flea beetles are a group of very small leaf beetles, usually of 

 metallic color. They are very active and jump vigorously when dis- 

 turbed. They eat very small holes through the leaves. The adults 

 of some species are rather general feeders on foliage while others 

 attack only one species or related species of host plants. The larvae 

 of most species live on roots in the soil but are generally not very harm- 

 ful in this stage. 



Flea beetles are difficult to control because the arsenicals are ap- 

 parently distasteful and repel them. However, fairly heavy doses 

 of lead arsenate, 2 to 3 pounds to 50 gallons of water, will give con- 

 siderable protection if thoroughly applied to all the foliage. Several 

 applications at about 10-day intervals may be required. 



Sap-Sucking Insects 



Sap-feeding insects cannot be controlled by stomach poisons, such 

 as the arsenicals, because the plant parts that would carry the poison 

 are not eaten. They feed by inserting their beaklike mouth parts into 

 the plant tissues and drawing out the juices. Contact insecticides, 

 that kill by coming in contact with the body, must be used. There 

 are a great many insects with sucking mouth parts, but the most com- 

 mon ones encountered in nurseries are the aphids and scale insects. 



APHIDS 



Aphids, or plant lice, are small, soft-bodied insects averaging about 

 the size of a large pinhead. Many are green but some are yellowish, 

 brown, or black. The sucking out of the sap from the stems or leaves 

 seldom kills the host, but heavy feeding may cause wilting, discolora- 

 tion, or even dwarfing of the seedlings. 



A number of generations are produced during a single season, and 

 the aphid population builds up rapidly under favorable conditions. 

 Infestations should, therefore, be treated early. The usual recommen- 

 dation for control is a spray made up of 1 pint of a 40-percent nicotine 

 sulfate solution in 100 gallons of water, and the addition of 3 to 4 

 pounds of common laundry soap or fish -oil soap as a spreader. In 

 smaller quantities, 1 teaspoon to 1 gallon of water plus a tablespoon- 

 ful of soap makes a comparable spray. Where directions for aphid 

 control are given on the container of the nicotine solution purchased, 

 these should be followed. Pyre thrum and derris compounds have also 

 been used successfully against aphids. 



SCALE INSECTS 



Scale insects usually resemble tiny scales of wax or very small galls 

 attached to the bark or leaves. They can be divided into three gen- 

 eral groups: (1) The armored scales, which are flattened and either 

 oystershell shaped, pear shaped, or rounded in outline, and covered 

 with a waxy excretion; included in this group are the oystershell scale, 

 San Jose scale, Putnam's scale, scurfy scale, and elm scurfy scale. (2) 

 The tortoise scales, which are tortoise-shaped or globular, and either 

 naked or with a portion covered with a cottony substance ; rather com- 



