58 EXPEEIMENT STATION RECOED. 



damage irrigated alfalfa nearly every j^eai". A i)reliiiiiiiary report based upon 

 studies made in 1910 has been previously noted (E. S. R., 25, p. 53). 



The species occurs throughout the United States west of the AUeghenies, and 

 in a few cases to the east and ranges northward as far as Hudson Bay. Tech- 

 nical descriptions are given of its several stages and an account of its life 

 history and habits. The egg stage has been found to vary under ordinary 

 temperatures from 2 to 15 days, the normal period being about 6 days. The 

 larva often completes its growth within 12 days, after molting four times and 

 increasing from less than one-tenth to nearly IJ in. in length. The average 

 length of the pupal period for ordinary field temperatures is from 7 to 10 days. 

 At Tempe, Ariz., never more than 200 eggs were recorded from one female, 

 whereas specimens sent to New IIanii)shire deposited as many as 500 eggs dur- 

 ing a laying period of 11 days, thus illustrating the influence of temperature on 

 egg production. The com])lete life cycle for this insect averages about 38 days 

 for all generations, the minimum length being about 2G days for the third 

 brood, and the maximum 64 days for the first brood. In the colder sections of 

 the country there are two generations, and in the extreme warmer sections at 

 least six and possibly more generations each year. 



The natural enemies of the pest include Trichogramma minutum, which para- 

 sitizes the egg; four hymenopterans, namely, Limneriiim n. sp., Apantcles 

 (Protopanteles) flavicomhe, Chalcis ovata, and Ptcromalus eurymi and the 

 dipterans Phorocera claripennis and AphiochcEta pcrdita, which parasitize the 

 larva and pupa ; and several predators, including the bollworm, which is preda- 

 ceous on the larva and pupa and prefers such food to alfalfa, the malachiid 

 beetle Gallops vittaius, the adult of which feeds on the caterpillars and pupjie, 

 the asilids Proctacanthus mdlbertii and Stenopogon picticoi-nis, and several 

 species of ants. A disease caused by an undescribed Fusarium and a bacterial 

 disease are said to cause a high mortality among the larvae and pupse, the lat- 

 ter being one of the most important factors looking toward its conti'ol. Birds 

 and domestic fowls, including turkeys, are also mentioned as important enemies. 



Studies of control measures have led to the following general directions: 

 Keep the ranch in the best possible cultural condition ; irrigate often and 

 thoroughly and as soon after cutting as the crop of hay can be removetl from 

 the ground ; renovate the field eveiy winter and during the month of August, 

 or even oftener if possible, either by disking or by the use of an alfalfa reno- 

 vator, and cut the alfalfa close to the ground and clean, especially along the 

 ditch banks, borders, etc. 



" Cut the alfalfa earlier than is the general rule. The proper time is when 

 it is just coming in bloom or is one-tenth in bloom. Watch for caterpillars in 

 the early spring crop, and if many are observed about grown, cut the hay a few 

 days before it is in bloom, and thus save the next and future crops. A minimum 

 amount of damage occurs in fields that are systematically pastured all or a part 

 of the time. 



"A field should never be abandoned because the caterpillars threaten the 

 destruction of a crop of alfalfa before the hay can possibly mature. Mow it at 

 once, cutting it low and clean, thus saving part of the present crop, and in so 

 doing starve, and allow the heat of the sun to kill, a great many of this genera- 

 tion of worms. Follow this by disking and then by either rolling or brush drag- 

 ging, and a great majority of any remaining larvre will be killed. The ground 

 should then be thoroughly irrigated, and by these efforts the coming crop will 

 be assured. Turkeys and chickens when allowed the run of a field will keep the 

 numbers of the caterpillars at a minimum." 



Surface caterpillar on Mokameh. Tal, E. J. Woodhotjse and H. L. Dutt . 

 {Agr, Jow: Bihar an4 Orissa [Indial, 1 {1913), No. 2, pp. 18-lOlf, pis. 4),— This 



