126 UNIVERSITY OP CALIFORNIA EXPERIMENT STATION. 



partly grown and spend the winter in a more or less dormant condi- 

 tion. There are generally two broods of the worms in California and 

 in some cases probably three. Any one of several species, however, may 

 increase to immense numbers, and they are then called army worms. 



They appear in large numbers as army worms, generally with the 

 second brood in midsummer. During the past year in the vicinity of 

 Lodi there was a distinct outbreak of army worms appearing simulta- 

 neously in a dozen or more different places. In nearly every case these 

 came from grain fields in which they bred, and because of the large 

 numbers and scarcity of food were forced to migrate, and as a result, 

 a number of vineyards were threatened with defoliation. These grain 

 fields or breeding places become pretty well dried up by August, and 

 furnish very little succulent growth for the voracious army worm. 



The worms appeared this year during the first week in August. They 

 had been feeding for a week or two in the grain fields, since some were 

 nearly full grown, but had not been observed to migrate until the date 

 mentioned. In one of these grain fields a contagious bacterial disease 

 killed them off by the thousands, and very effectively checked their 

 progress. Portions of a number of young vineyards were defoliated 

 before their presence was realized. The species concerned here was the 

 true army worm of the Eastern States, which bears the scientific name 

 of Heliophila unipuncta. In bearing vineyards, besides eating off the 

 leaves, these worms have the pernicious habit of cutting off the stems 

 of the clusters of fruit, which drop to the ground and dry up. In a 

 portion of a bearing vineyard near Lodi, where these pests were present, 

 this unripe fruit was picked up, while still fresh, by the basketfuls and 

 made into jelly. 



These caterpillars are mostly dull-colored worms from one to two 

 inches long, with longitudinal strips of black, gray and yellow or red- 

 dish brown. There is considerable variation in color in the same 

 species, some being much darker in color. Generally the midsummer 

 brood from which the army worms arise are darker colored than the 

 spring brood. The one present in Lodi and vicinity this year (see Fig. 

 16) had a broad black velvety stripe on the dorsal side. Below this 

 was a stripe of whitish yellow about one half the width of the former, 

 with its center made up of broken wavy lines. Below this was another 

 narrow stripe of black with the spiracles on the lower edge; back and a 

 little above each spiracle was a conspicuous white spot that on first 

 sight would be taken for the spiracles themselves. Below this is another 

 stripe of light brown, and on the ventral surface a general color of 

 cinnamon brown. 



Control Measures. The cut worm, although belonging to the same 

 group as the army worm, on account of the difference in habits must 

 be controlled in a different way. Since it is those species which acquire 



