540 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



Fig. 1. Scurfy Scale. Purdue Bulletin U.S. 



t'onfrol 



Same as for San Jose scale. 



E. 0. EssiG 



Seventeex-Year Locust. — See Periodi- 

 cal Cicada, this section. 



Six-Spotted Spider. — See Red Spider. 

 this section. 



Synet.\. — See Fruit Tree Leaf Syneta. 

 this section. 



Tent Caterpillars 



Malacasoma erosa Stretch. 



Malacasoma pUrviaUs Dyar. 



Malacasoma roiistrirta Stretch. 



By H. F. WiLSox 



Tent caterpillars, so-called because they 



build nests wherein they usually remain 



when not feeding. These nests are formed 



out of silken threads secreted by the lar- 

 vae and serve both as a shelter and a 

 protection against natural enemies. 



Of the many different species which 

 exist throughout the world only three are 

 at all serious in the Northwest. To the 

 casual observer there is little difference 

 lietween the larvae and adults of these 

 species when looked at separately. Taken 

 side by side, however, the full-grown lar- 

 vae may be easily distinguished, one 

 species from the other. 



*According to Professor F. L. Wash- 

 burn, a former entomologist of the Oregon 

 Agricultural College, of the three, Malaca- 

 soma erosa, Malacosoma pluvialis, and 

 Malacasoma constricta, the first named 

 feeds upon almost everything but the pear, 

 viz.: apple, quince, cherry, rose, prune, etc. 

 The second has about the same food plants 

 as the first. The third devastates whole 

 groves of oak, particularly Quercus gar- 

 ryana, occasionally migrating to the 

 prune, and thereby causing considerable 

 alarm among orchardists. 



During the past two or three years M. 

 pluvialis has been extremely abundant in 

 the western part of Oregon, both on fruit 

 and forest trees. Numerous reports have 

 come in from about Portland and I have 

 observed the larvae over many square 

 miles of woodland in Southern Oregon. 



When these larvae are very numerous 

 they can entirely strip a tree of its fo- 

 liage in a very short time. When first 

 hatched from the eggs they are not read- 

 ily noticed, but as they grow larger they 

 are readily distinguished both by their 

 size and by the tents which they build. 

 Toward the middle or latter part of the 

 summer the larvae become full grown; 

 they then seek crevices where they spin 

 silken cocoons and change to pupae. After 

 remaining in this stage a short time they 

 change to the adult insects or moths 

 which come forth and deposit the eggs. 

 The eggs are deposited in masses on the 

 small branches or shoots, and in the case 

 of one species, where the eggs are laid 

 on new shoots, the egg mass completely 

 surrounds the twig. These are covered 



♦F. L. W.ishluini. Bullelin 33. Oics.m Ex- 

 pn-iment Stnii<;n. 1S04. 



