BIRDS m RELATION TO THE ALFALFA WEEVIL. 31 



Five stomachs of this species were available for June, and in 

 every one the weevil was found. A large quantity of caterpillars in 

 two stomachs reduced the percentage of weevils taken, but the results 

 show that in this month the savannah sparrow is continuing the good 

 work started earlier in the season. The weevil composed 37.4 per 

 cent of the stomach contents and an average of a little over 1 adult 

 and 11 larvae were taken by each bird. The other food, again almost 

 wholly animal, contained, besides nearly 30 per cent of caterpillars, 

 a quantity of spiders, estimated at a little over a fifth of the food. 

 This latter item was present in four of the five birds and was prac- 

 tically the only food which could not be considered in the bird's 

 favor. 



Nine stomachs collected in July reveal in a most striking manner 

 the worth of this insectivorous sparrow as an enemy of the weevil. 

 All of these birds had eaten the insect, and in six instances it amounted 

 to 90 per cent or upward of the food, the average consumption for 

 the month being 80 per cent. These birds were collected in the 

 Weber Valley, where larvae were very abundant, and they fed on the 

 insect at the rate of 16^ larvae and a little less than 2 adults per bird. 

 The highest number eaten by a single bird was 26 larvae and 1 adult. 



Of the remaining food Hemiptera formed the largest portion 

 (7.67 per cent). Included here are many small bugs of the genus 

 Corizus. Caterpillars composed about 5| per cent. The vegetable 

 portion, 2.22 per cent, was entirely weed seeds. 



Summary. — Of the native sparrows of Utah probably none can 

 equal the western savannah as a destroyer of the alfalfa weevil, un- 

 less, under favorable conditions, it may be the western chipping or 

 Brewer's sparrow. It not only appears to be the most highly in- 

 sectivorous of the fringilline birds in this area, but also includes in 

 this diet more than an ordinary share of weevils. During May, 

 June, and July this insect forms from a half to two-thirds of its 

 food, sufficient evidence in itself to induce every farmer to become 

 familiar with the savannah sparrow and encourage its presence 

 about infested fields. 



WESTERN LARK SPARROW. 



(Chondestcs grammacus strigatus.) 



The lark sparrow, one of the most robust and conspicuously 

 marked of western sparrows, is found in abundance throughout the 

 Salt Lake and Weber Valleys, and occurs in approximately the same 

 numbers wherever found. It is frequently seen about alfalfa fields, 

 and is one of the effective bird enemies of the weevil. 



It is common by the first of May, and the 14 birds collected in this 

 month show that they already were capturing breeding adults. 



