APPLE PESTS 



543 



Unicorn rroniinent 



Schizura unicornis 



During August and September, a sin- 

 gular caterpillar is occasionally found 

 feeding on apple foliage. It is reddish 

 brown, variegated with white on the back, 

 and has a green patch on each side, ex- 

 tending over the second and third seg- 

 ments, while from the top of the fourth a 

 conspicuous horn is projected. It eats out 

 a notch from the edge of the leaf and 

 then fits itself to the notch, clasping the 

 eaten edge of the leaf with its prolegs 

 while the prominent horn is made to ex- 

 tend over a portion of the vacant space 

 where belonged the devoured tissue. The 

 outline of the back, thus simulating the 

 irregular edge of the leaf, enables the cat- 

 erpillar to elude the sight of all but the 

 most searching eyes. This caterpillar is 

 known as the unicorn prominent, and 

 though interesting, rarely, if ever, be- 

 comes sufficiently numerous to be troub- 

 lesome. It reaches full size in Septem- 

 ber and descends to the ground, where a 

 cocoon is constructed under the fallen 

 leaves and trash. The light-brown moth 

 does not appear until the following sum- 

 mer. No measures against this insect 

 are needed under ordinary circumstances. 

 If a. midsummer spraying with arsenate 

 of lead Is made in July or August, these 

 caterpillars are apt to be thinned down 

 until they attract no notice. 



H. A. GOSSABD, 

 Wooster. Ohio. 

 Weetil.— See Bronze Apple Tree Wee- 

 vil, this section. 



Western Tussock Moth 



Hemerocampa vetusta Boisd. 

 H. F. Wilson 



The distribution of this insect in the 

 United States is at present limited to the 

 Pacific coast, and on account of the sim- 

 ilarity of its work to that of the tent 

 caterpillars, is often taken for one of 

 those insects. The two are quite differ- 

 ent, however, in appearance, both in the 

 larval and adult stages. 



The eggs begin to hatch about the time 

 the leaves are spreading out in the spring, 

 and at that time the young larvae are 

 almost black. For a few days they re- 



Fig. 1. Western or California Tussock Moth. 

 (at and (b) Adult wingless females. (d) 

 Cocoons. le) Egg masses attached to the 

 cocoons, (t) Eggs, (g) Internal parasite 

 working upon cocoons. ^Essig. ) 



main clustered about the egg mass and 

 apparently feed on the substance which 

 covers and holds the latter together. 

 After the larvae have all hatched and 

 have broken out from the eggs, the egg 

 mass will appear as if riddled with holes. 

 The larvae cut these in escaping from the 

 eggs. 



After a few days the larvae spread on 

 to the nearby buds and leaves. At first 

 the damage is very slight and consists of 

 minute holes in leaves, blossoms and fruit. 

 Later they feed entirely on the leaves 

 which they devour, leaving only portions 

 of leaves and the larger veins. 



Unlike the larvae of the tent caterpil- 

 lars, they spread out over the tree and 

 do not collect at night nor do they build 

 nests or tents. They are somewhat wan- 

 dering in their habits and oftentimes can 

 be seen crawling about on the ground, go- 

 ing from one tree to another. 



The original description of the larvae 

 is given as follows: "Ground color vel- 

 vety black. Head black, rather shining, 

 with yellow line in front. From the sec- 

 ond segment springs two bundles of long 

 black hairs. The space between these is 

 bright vermilion red: at the base of each 



