Can ‘mosquito eater' insects be harmful to your garden?
Q: Last fall, we saw a lot of "mosquito eaters" around our backyard. Are they harmful? Why were there so many?
Crane flies (a.k.a. "Mosquito eaters") are generally harmless insects that resemble gigantic mosquitoes. They usually appear later in the summer or fall, but can show up any time of the year. The adults have a 10-15 day lifespan during which they may feed only tiny amounts of nectar or nothing at all. They are attracted to light and are food for birds, bats, and some predatory insects such as ground beetles. Crane flies lay their eggs in moist environments, particularly in cool-season turfgrass with poor drainage.
Their larvae, called leather jackets, remain in this juvenile state for a surprisingly long time -months or sometimes years. They can cause damage to grass roots, though this is more common in cooler areas. If you are seeing large numbers of adult crane flies and/or turf damage, check your irrigation system and drainage.
Q: What is winter chill, and why is it important?
One way to calculate winter chill is to count the number of hours that the ambient temperature is between 32 and 45 degrees (Fahrenheit). Hours below 32 degrees don't count, and hours when the temperature is greater than 65-70 degrees are deducted from the total. I've seen winter chill hours calculated by other formulas, but this should give you a general idea.
Winter chill allows the plant to rest and reset during its dormant period. Think of it as nap time for your tree. If a high-chill tree does not get enough winter chill, it will fail to flower or set fruit. When it comes out of dormancy, it may produce only a few leaves at the very tip of its branches, leaving the rest of the wood bare (terminal leaf-out). Eventually, the tree will decline and die.
When selecting fruit trees to grow in Southern California, look for those with the lowest winter chill requirements. Generally, apricots, peaches, and nectarines will grow well here since they have lower chill requirements. Some apples and pears will grow and produce here, but others will not. Cherries, usually grown in Michigan and other, much colder regions, will not produce well here and may die after a few years. If you want to try your luck with a borderline tree, sometimes you can take advantage of local microclimates and plant at the bottom of a hill, away from any heat sinks such as concrete walkways, walls, fences, ponds, or under eaves.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu
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This story was originally published May 22, 2026 at 1:03 PM.