A reader wrote to us a few days ago about some large, plump white worms that he found in a mulch pile on his lawn. The reader thought they were grubs, which are often called “grub worms” or “grubworms” (even though they are actually larvae), but thought that they might be too big to be grubs, in part based on information he read on this website. The creatures our reader found are in fact quite large – they are about three inches (7.5 centimeters) long and one inch (2.5 centimeters) wide – but they nevertheless appear to be grubs. Did our reader find grubs in the mulch pile on his lawn, or are the creatures he found too big to be grubs?
The reader sent an excellent photo of the creatures he found, so we’ll begin by taking a look at that:
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The picture our reader sent had even more grubs in it, but we focused in on the creatures we can see most clearly. There is no real scale in the image, so it is difficult to confirm our reader’s measurements, but whatever he found does look pretty large.
The reader referred to what he found as “worms,” perhaps in part because he thought he couldn’t have found grubs, but we are virtually certain these are not worms, but rather some type of insect larvae, and we know this because the creatures have three pairs of legs. This can’t be determined by looking at the image above, but at the very bottom of the picture our reader submitted is this larva:
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And you can tell that it has three legs on one side of its body, and thus presumably has three matching legs on the other side of its body. So, our reader is finding insect larvae, but what kind?
As we stated at the beginning, we do think he found grubs, which are the larval form of beetles, in spite of their large size. The grubs we have answered questions about are definitely a lot smaller than three inches long and an inch wide, and the grubs people generally find on their lawns in Texas (where our reader lives) are also a lot smaller than this. For instance, there is a fairly comprehensive guide to grubs in Texas published by the Texas A&M extension program, and they report (or, technically, imply) that the grubs people find on their lawns in Texas (generally June beetle larvae) reach only about an inch in length. So, our reader may have found information about grubs on this site that implied that they are smaller than three inches long, but this only reflects what seems to be generally true of grubs. Additionally, it would be strange if most grubs reached a length longer than an inch when you consider the size of most adult beetles. Larvae can be a little larger than the adult forms they grow into, but they generally aren’t several times larger.
That said, it is important to note that “grubs” is a fairly imprecise word, and there are lots of different species of grubs, so there isn’t really a “standard” grub size. Even if you restrict the word “grub” to only mean the larval form of scarab beetles, as some people do, this still means there are over 30,000 species of grub. It is difficult to formulate any size rules when you are talking about tens of thousands of species. Moreover, grubs evidently can reach larger sizes, as there are lots of pictures online of fairly substantial grubs – ones that look very much like what our reader found.
Thus, we don’t know exactly what kind of grub our reader found, and in fact we can’t even be certain he found a grub (however we understand that word), but it seems likely that he found one, and their size doesn’t preclude this possibility. Perhaps he just found a group of particularly large grubs, lending credence to the claim that everything is bigger in Texas.