176 ANNUAL REPORT OF THE Off. Doc. 



(4) INVESTIGATIONS 



But little time has been found for investigations, yet it is neces- 

 sary to make certain exjjeriments and investigations along certain 

 lines in economic entomology. jSiew insecticides are constantly com- 

 ing on the market, and our citizens are making inquiry concerning 

 their value. We can not answer such inquiries without personal 

 experiments, as many of the materials are too new to have been 

 tested and reported by other persons. 



For example, we found last summer by practical test that the dry 

 sulfur compounds on the market for spraying are quite liable to 

 burn the foliage of plants. Many persons reported to us disastrous 

 results from the use of such material, which, in general, is not lime- 

 sulfur compound but soda-sulfur, and hence very caustic. 



In our investigations of life histories and habits of destructive 

 insects, one of unusual interest was taken up. This was the Red 

 Leaf Beetle (Galerucella cavicolUs). The results of these studies 

 are described in the following Press Circular: 



"NEW PEST ATTACKS FRUIT TREES. 



Important discoveries in the habits of the Red Leaf Beetle, re- 

 cently found in Pennsylvania, have been made by Zoologist H. A. 

 Surface of the Department of Agriculture. Professor Surface after 

 exhaustive investigations has been able to report on the native food 

 plants, habits and remedies of the Red Leaf Beetle, which formerly 

 were not known, and which have never before been published. 



The insect has been very destructive in several counties in the 

 northern and central portions of Pennsylvania, feeding upon foliage 

 of cherry, peach, apple, pear and some other trees, shrubs and plants. 

 It has been proven that the native food plant of the mature beetle, 

 as well as its larva, is the Pennsylvania fire cherry (Prunus Penn- 

 sylvanicus). The larvae do not feed on any other kind of plant, but 

 they completely defoliate the wild fire cherry, which is the species 

 of wild cherry with small fruits hanging in clusters on bunches, 

 which are red in color when ripe. 



In the mountain districts from the central part of Pennsylvania 

 northward this fire cherry grows very abundantly, and it is in this 

 region that the Red Leaf Beetle has proven destructive in the past 

 two years. An important practical point is to be noted, that while 

 the mature beetles feed on the leaves of many kinds of trees, espe- 

 cially the cultivated cherry, peach and plum, and sometimes upon 

 apple and pear, they do not lay their eggs upon these cultivated 

 trees, laying on the fire cherry only, and the larvae of this species of 

 beetle have never been found damaging any other kind of plant than 

 the wild fire cherry. 



The life history of this insect was worked out by the Department 

 of Agriculture through representatives of the Bureau of Zoology, 

 and was found to be as follows : The beetles in the early part of the 

 summer feed on the leaves and crawl down the trunks of the fire 

 cherry trees to or near the surface of the ground, where they deposit 

 their eggs at the base of the tree trunk, and on the surface of the 

 ground and in rubbish. After a few daws in the form of the small 

 yellow eggs there hatch dark green grubs, which climb the trunks of 

 the trees, feed on the leaves, molt and become lighter in color. As 

 they cWmpletie their growth they go down to the soil to pupate or 



