the larvae of which devoured the celery leaves in large numbers. Two other 
types of moth larvae, namely the celery looper (Autogrepha falcifera) and 
the cutworm (Phalacnidao) also ceused considerable eee ee The demage is 
most Severe during mild vinters when the tempercture cverages a little above 
normal throughout the growing season, which oxtends eet December to the end 
of Merch. The harvest continues until late in April, and occasionally a 
late crop is harvested in June. 
E. D, Ball, who conducted & detsiled study or the celery insect pests 
for the Flerida ¢ a ane) del kouali; Bocra, neported that during warm weather three 
insect parasites helocd to keep the celory leaf-tier in check. By far the 
‘most important of these is a tiny black wasp (@richog ramme. minutum) , which 
lays Hts ege@s in the eess of the Lexfpticr. During & novmal winver, how- 
ever, this wesp becemes inactive for several months, «nd Since most of the 
celery growth takes place during thet period, en influx of migrant birds 
serves as the principal netural oe On) URS) ease etl peSiiSis 
Four specics of birds were found to be of primary importmce in the 
ntrol of the celery lcéf=-tier. These were the gela warbler (Dendroica 
eee ), tree swallow (Iridoprocne bicolor), red-winged blackbird 
Ageleius phoeniceus), and, near the end of the ha vein season, the 
bobolink (Dolichonyx oryzivorous) . 
The palm warbler wes more widely distributed in large numbers through- 
out the celery arce during the entire growing Season then any other bird. 
The western race (D. p..nalmarum) outnumbered its eastern relative, the 
palm werbler)(D.».. hynochrysea), by about 25.to 1. These eee 
Were OCceestonel iy sound in the woods) but typically they ane Lovers) of 
Open ficlds with brushy borders om scctvered trees. 
the palm warblers showed little fear of man ond Were (CUA Me! aia lie 
Celery ficilds throughout the day, feeding even during the middey heat, 
when most Other birds remained quiet. Twenty-three of these Werblers were 
collected for stomach excmination, end 22 of them were found to contain 
celery leef-tiers in all stages of metamorphosis. This insect pest made up 
75.14 pe-cent of the total volume cf food exten by the palm.warblers, and 
other lepidopterous pests Wolo cutworms) composed en additiom 1 6.09 
percent. Some Of the Svomachs Conveined as many. as 54 leaf-—tiers; the 
werage for the series wes 13. The birds worked far down omong the stems 
of the celery plants <¢nd removed the insects with surprising thoroughness. 
Tree swallows also rendered .great Service in reducing the number of in- 
sect aaa The celery crop was commonly dusted with pyrethrum in an ef- 
fort to. drive out the adult lect=tiers. when the cust wes auphied 4.7 the 
Colony whe moOuls) Coula dary inFo the clr in Shor Gs) flies) and den ance 
back into the field. This procedure wes continued ‘until the insects finally 
escaped) irom ine dusted: area. Lhe beeinning on Gusting operations im any; 
field served as e Signel for all the tree swallows in the vicinity to con- 
Cenvtrate over thie infested ares. Hundreds would swarm around the duster 
ANG WOVeR i Meer Wh as io Greversed thc tilelds) Deco Bella stated thet the 
effectiveness of pyrethrum in controlling the adult leef-tiers was propor- 
tionate to the assistance given by swallows. In one series of observations 
mede while Tyine prone between the celery rows he found thet only 2 of the 
fins LOO moths that arose during dusting operations La whe remarkable 
